US2003171A - Telescope - Google Patents

Description

May 28, 1935. E. P. BURRELL TELESCOPE .Filed Jan. 15, 1932 9 Sheets-Sheet l Avvavrae W AKA/2M r4770PA/EYS May 28, 1935. E. P. BURRELL TELESCOPE Jan. 15, 1932 9 Sheets-Sheet 2 Filed y 1935. E. P. BURRELL 2,003,171

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Arraemsr I WINK-HIM May, 28, 1935. E. P. BURRELL 2,003,171

TELESCOPE Filed Jan. 15, 1932 9 Sheets-Sheet 8 g/w Maw/6 UNITED STATES PATENT OFFICE aooarzr 'rsrssoora EdwardP. Burreii. Shaker signer to The Warner a Heights, Ohio, as-

Swasey Company,

Cleveland, Ohio, a corporation of Ohio Application January 15,

39 Claim.

This invention relates to a telescope.

Although the invention in all or in some of its aspects is applicable to both the refractory type and the reflector type of telescope, it will be described herein in connection with the last mentioned type of telescope since it has especial utility when applied thereto.

An object of the invention is to provide a com struction for a telescope that combines lightness with strength, which possesses rigidity, perfect balance and accuracy, and which may be more economically produced than telescopes constructed in accordance with the heretofore known methods.

Another object is to provide a construction for a telescope wherein the various units forming the tube which supports the optical system of the telescope are made up of structural metallic members.

Another object is to provide a telescope where'- in the tube is made up of shaped and formed structural metallic members integrally united by welding.

A still further object is to provide in a telescope a structural metallic support for the main or primary mirror and improved and novel means for mounting said mirror in such support.

An additional object is to provide in a telescope a structural metallic support for the secondary mirror together with improved and novel means for mounting the secondary mirror in such support.

A still further object is to provide in a telescope improved and novel means for detachably mounting the secondary mirror in its support whereby mirrors of different types may be interchangeably supported in the telescope.

Another object is to provide in a telescope improved means associated with the support for the secondary mirror and enabling such secondary mirror to be moved to and locked in a plurality of different positions to allow observations to be made from a number of different stations.

Another object is to provide in a telescope an improved construction for the center piece of the telescope which includes a mounting plate by which the tube is connected to the supporting axes of the equatorial mounting of the telescope.

Additional objects and advantages of the present invention will become apparent hereinafter during the following detailed description of embodiments of the invention.

The embodiments of the invention which are to be described herein are illustrated in the accompanying drawings, wherein 1932, Serial No. 586,920

Fig. l is a diagrammatic view showing a telescope having an equatorial mounting of the crossaxis type in which there is a single supporting connection between the telescope tube and the equatorial mounting, i. e.'the side of the tube is 5 connected at a single point to the axes.

Fig. 2 is a diagrammatic view of a telescope having an equatorial mounting of the fork type in which there is a two-point supporting connection between the telescope tube and the 10 equatorial mounting, i. e. both sides of the tube are supported in the fork of said mounting.

Fig. 3 is a detached elevational view of a telescope tube embodying the present invention, with some of the counterwelghts at the inner end and the eye-piece adapters at the outer end, not shown.

Fig. 4 is a fragmentary sectional view oi. the tube on an enlarged scale. the section of the center-peice being taken substantially on line 44 of Fig. 8, looking in the direction oi the arrows and the section of the mirror cell being taken substantially on line la -4a of Fig. '7, the center piece here shown having diametrically opposed mounting plates for use with an equatorial mounting of the fork type;

Fig. 5 is an end view on an enlarged scale taken from the left-hand side of Fig. 3 with certain cover plates removed to illustrate other details;

Fig. 6 is an end view on an enlarged scale taken from the right-hand end of Fig. 3;

Fig. 7 is a detached end'elevational view of the mirror cell taken from line i! of Fig. 4, looking in the direction of the arrows, the mirror being omitted and a portion only or the mirror clamping means being shown in full lines, the remainder being indicated in dotted lines;

Fig. 8 is a sectional view taken substantially on line 88 of Fig. 4 looking in the direction of the arrows, certain of the parts being omitted in 49 this view, the center piece being shown as provided with only one mounting plate for use with an equatorial mounting of the cross axis type.

Fig. 9 is a sectional view taken substantially on line 99 of Fig. 6, looking in the direction of the arrows;

Fig. 10 is a sectional view taken substantially on line [0-H] of Fig. 9, looking in the direction of the arrows;

Fig. 11 is a view similar to Fig. 9 but showing a different form of secondary mirror and a different form of support for said mirror;

Fig. 12 is a fragmentary sectional view taken substantially on line |2|2 of Fig. 6 looking in the direction of the arrows;

Fig. 13 is a fragmentary sectional view on an enlarged scale taken substantially on line I3-il of Fig. 3, looking in the direction of the arrows with the eye-piece adapter shown in position.

Fig. 14 is a detached view partly in section of one of the adjustable supporting members for the primary mirror;

Fig. 15 is a fragmentary sectional view taken substantially on line 15-45 of Fig. '7, looking in the direction of the arrows;

Fig. 16 is a fragmentary sectional view taken substantially on line i6l3 of Fig. 8, looking in the direction of the arrows;

Fig. 17 is a fragmentary elevational view taken from the left-hand side of Fig. 16;

Fi 18 is a fragmentary plan view taken. from the top of Fig. 17;

Fig. 19 is a fragmentary sectional view showing the construction of one of the joints of the tube and is taken substantially on line l9-l 9 of Fig. 3, looking in the direction of the arrows, the tie rodsbeing omitted;

Fig. 20 is a developed view of the parts forming the joint of g. 19 to illustrate their shape prior to being ass mbled and integrally united by welding;

Fig. 21 is a fragmentary end view taken from the right-hand side of Fig. 3 and showing another of the joints of the tube;

Fig. 22 is a developed view of the parts forming the joint shown in Fig. 21 and illustrates such parts prior to their being assembled and integrally united by welding;

Fig. 23 is a fragmentary sectional view similar to Fig. 19 but showing, in addition, the tie rods assembled and welded in place.

Fig. 24 is a front view of the joint shown in Fig. 23;

Fig. 25 is a fragmentary front elevation of one of the joints of the tube near the outer or righthand end of Fig. 3; and

Fig. 26 is a side elevation of the joint shown in Fig. 25 looking from the right-hand side of Fig. 25.

Before proceeding with the detailed description of the embodiments of the invention illustrated in the accompanying drawings, it Will be well to state that the present invention contemplates a novel and improved construction for the tube of a telescope, a novel support for both the primary and the secondary mirrors and a novel mounting plate by which the tube can be connected to the supporting axes of the telescope.

Although the invention is applicable to telescopes of the refractory type, it is particularly adapted to be applied to telescopes of the reflectory type and for that reason has been so illus trated herein. In telescopes of the reflectory type the optical system of the telescope is arranged in what is known as the telescope tube, which tube consists of three main elements, namely, a cell 30 in which the primary mirror is adjustably mounted, a center piece 3| by which the tube as a whole is supported upon the supporting axes and to which the cell is removably attached, and a framework 32 attached to the center piece and extending toward the focus of the primary mirror for the purpose of supporting the secondary mirror, which mirror may be either of the Newtonian type or of the Cassegrain" type, as hereinafter referred to, to allow observation from different stations.

The center piece of the tube is connected to the supporting axes of the telescope, which axes constitute the equatorial mounting for the telescope. The equatorial mounting may take various forms, two of which are diagrammatically illustrated in Figs. 1 and 2 respectively. In Fig. l the tube is shown as supported upon an equatorial mounting of the cross axis" type, wherein the center piece of the telescope tube is connected at one side'only to the declination axis of the mounting, indicated at 33, and enabling the tube to be rotated in a plane parallel to the earths axis. The declination axis 33 is rotatably supported by the polar axis and at right angles thereto, such polar axis being indicated at 34, and arranged to rotate about an axis parallel to the earth's axis, the motion of the tube about the polar axis being known as motion in right ascension.

The equatorial mounting of the fork" type is illustrated in Fig. 2 wherein the polar axis 34a is provided with an overhanging fork 35 straddling the center piece of the telescope tube and supporting the declination axis 330, the latter axis being connected to the center piece 3| at two diametrically opposite points thereof.

In an equatorial mounting of the cross axis type the polar axis 34 is supported at its opposite ends by bearing supports and the declination axis 33 is mounted on the polar axis intermediate the supports therefor, thus allowing the telescope tube to swing about the polar axis and in addition to swing about the declination axis 33. In an equatorial mounting of the fork" type the polar axis 34a is mounted in bearing supports arranged at its end and intermediate its end, while the fork of the polar axis is located outwardly of the last mentioned bearing support. The telescope tube in the forkftype of mounting also may rotate about'the polar axis and in addition about the declination axis 3311.

In any form of equatorial mounting the telescope tube may be moved about an axis parallel to the earth's axis and about an axis at right angles thereto, the last named motion of the tube being in planes parallel to the earth's axis. The mechanism for moving the telescope tube about the two perpendicular axes has not been illustrated herein since it is well understood in the art and forms no part of the present invention.

The construction of the primary mirror supporting cell 30 is clearly illustrated in Figs. 3, 4, 5, 7 14 and 15 and reference to these views should now be had. The cell comprises a sheet metal circular sleeve 36 to the outer side of which a metal ring 31, formed of angular structural metal, is secured by welding the same thereto, it being noted that the ring 31 is located inwardly of the end of the sleeve 36, so as to provide a projecting portion of the sleeve for a purpose later to be explained. The ring 31 is provided with a number of circularly spaced reinforcing ribs 38 which are made of plate metal and welded to the arms of the ring 31.

A second structural metallic ring 39 of angular cross-section is welded to the interior of the sleeve 36 at its opposite end, the ring 39 having one of its arms extending radially inwardly of the open end of the sleeve, as clearly shown in Fig. 4. Three I-beams, designated at 40, see Figs. 4, 5 and 7, extend across the open end of the sleeve 36 adjacent to the ring 39 and have their opposite ends welded to the sleeve 36, to both arms of the ring 39 and to each other, thus forming a rigid and strong construction for the primary mirror supporting cell. Between the I- beams 40 and the ring 39 there are arranged short I-beams H which are welded at one end to the I-beams 40 and at the' opposite end to the sleeve 36, to both arms of the ring 39 and to each other. Between the I-beams 40 and offset inwardly with respect to the I-beams 41 are 1- beams 42, having their opposite ends welded to the I-beams 40 and being provided intermediate their ends with reinforcements 43 in which are threaded openings for screws 44, the purpose of which will later be explained.

The arm of the ring 39, which extends radially inwardly oi the open end of the sleeve 36, is provided with a plurality of reinforcing bosses 45 welded to the ring 39 for the purpose of supporting counterweights 46. The same arm of the ring 39 is provided with a plurality of substantially equally spaced openings receiving bolts 41 which extend inwardly of the cell and adjustably support at their inner ends a shouldered ring 46 forming a seat for the primary mirror.

A plurality of centering supports for the primary mirror are carried by the sleeve 36 and ring 31 and are illustrated herein as being four in number, two of which are fixed and two of which are movable and adjustable. The fixed centering supports are indicated at 49 and are in the form of segmental shoes secured to reinforcing strips 50 and to the sleeve 36 and ring 31 by screws 51 extending through the ring 31, sleeve 36 and strip 56 into the shoe 49. The movable and adjustable supports comprise shoes 52 arranged in the cell and located substantially diametrically opposite to the fixed supporting shoes 48. The supporting shoes 52 are prevented from endwise movement by adjustable pins 53 extending through the ring 31, sleeve 36 and reinforcing strips 56 and projecting into recesses formed in the shoes intermediate the ends thereof. The shoes 52 are arranged to be radially adjusted by means of adjusting screws 54 carried by threaded sleeves 55 having at their inner ends shoulders extending into recesses in the shoes, which sleeves project through openings in the sleeve 36, ring 31 and reinforcing plates 56 secured to the outer side of the ring 31. Coil springs 51 surround the sleeves 55 and abut the shoulders at the inner ends of the sleeves and the under sides of the reinforcing plates 56.

The inner ends of the adjusting screws 54 extend into openings formed in the shoes 52 and are provided with hardened steel balls 58 engaging shouldered pins 59 carried by the shoes 52 to allow the shoes to have a slight rocking move ment in order to seat themselves correctly against the outer circumference of the primary mirror.

. Nuts 60 arranged on the sleeves exteriorly of the cell enable the tension of the springs 51 to be adjusted, while turning movement of the screws 54 enable the shoes 52 to adjust themselves radially inwardly or outwardly of the cell. It will be understood that the purpose of the springs 51 is to compensate for variations in the diameter of the primary mirror occasioned by the expansion and contraction thereof at different temperatures, and that when the tube is swung to various positions the springs are capable of carrying the weight of the mirror. Angle plates 61 are secured to the inner side of the sleeve 36 adjacent the fixed supporting shoes 49 and the adjustable supporting shoes 52 to support the same and to prevent lateral displacement of the adjustable shoes.

As previously mentioned the I-beams 42 are provided intermediate their ends with reinforcements 43 in which are threaded openings for screws 44, see Figs. 7 and 15. The inner ends of the screws 44 are reduced and provided with spherical portions 62 extending into recesses formed in members which serve to clamp the clamping members are swivelly connected to the" screws 44 by means of the spherical portions 62 and that therefore the clamping members and particularly the clamping portions 64 will adapt.

or adjust themselves to the proper clamping position with respect to the rear side of the primary mirror. The connecting portions 63 of the clamping members are provided on each side of the recesses into which extend the screws 44 with recesses 66 and into which extend pins 61 carried by the I-beanis 42. The purpose of the recesses 66 and pins 61 is to prevent the clamping members from turning about the screws 44 as an axis, it being noted that the pins 61 do not extend to the bottom of the recesses 66 and therefore do not prevent the rocking or swivelling movement of the clamping members previously referred to.

The primary mirror 66, see Fig. 4, is provided with a concave reflecting surface 69 and with a centrally arranged opening 10. The primary mirror 66 is entirely supported by the cell 36 and can be arranged in the cell before the same is assembled to the center piece thus facilitating the removal of the primary mirror for resilvering or for other purposes. In assembling the primary mirror in the cell the shouldered seat 46 is first removed and the mirror is then inserted in the cell between the fixed and adjustable centering supports 46 and 52, respectively, and against the portions 64 of the clamping members which have been adjusted to approximate position, the insertion of the mirror taking place through the righthand side of the cell, as viewed in Fig. 4. The mirror having been thus inserted the seat 48 is positioned upon the circumferential edge of the mirror adjacent the concave side thereof and the bolts 41 screwed into the tapped openings formed in the seat to draw the latter tightly against the edge of the mirror. It is now merely a' matter of adjusting the mirror axially by means of the bolts 41 and the screws 44 and radially by means of the screws 54 that adjust the centering supports 52, it being noted that all of these adjustments may be readily performed from the outside of the cell after the cell has been assembled to the center piece.

A circular plate 11 is arranged at the rear or left-hand side of the cell, as viewed in Fig. 4, and is welded to the I-beams 46. and 42, see Fig. 5. The plate 1! is provided with an annular shoulder 12 and with a central opening for a purpose which will be referred to hereinafter. An eyepiece adaptor is supported by the plate 1! and centered by means of the annular shoulder 12, which adaptor comprises a circular plate 13 seating against the outer surface of the plate 1| and the shoulder 12 and secured thereto by means of screws 14. The plate 13 is provided intermediate its ends with a laterally extending annular hearing flange 15 upon which a Worm wheel 16 is rotaiably mounted. This worm wheel 16 is held in position upon the bearing flange 15 and against axial displacement by means of a retaining ring 18 secured to the plate 1| and the plate 13 and having a portion 18a forming a housing for a. worm 19 and bearings for the worm shaft 8D,

which may be rotated by a hand wheel and. shaft 8| supported on the outside of the cell, as clearly shown in Fig. 5. The rotation of the worm 19 causes rotation of the worm wheel '16 upon the bearing flange 15 and, since the eye-piece adaptor 82 is secured to the worm wheel, it will be seen that the adaptor will also be rotated by the worm to any desired position. The adaptor 82 is provided with a bore 83 axially aligned with the opening 18 in the primary mirror 68 and the central opening in the plate there being secured to the adaptor 82 at the outer end of the bore 83 a split collar 84 in which a suitable eyepiece mounting may be clamped and supported, in this instance a cover plate 85 being shown in position in place of an eye-piece support. The eye-piece adaptor 82 is provided with a second bore 86 arranged at right angles to the bore 83 and having a split sleeve 81 secured therein adjacent its outer end. An eye-piece support 88 extends through the sleeve 81 and the bore 86 and is supported therein with its inner end located within the bore 83 and provided with a prism 89 to reflect the light beam passing through the opening in the primary mirror and the bore 83 at right angles to an eye-piece which may be carried by the eye-piece support 88. From the foregoing description it will be seen that observations may be made centrally through an eye-piece carried by the eye-piece support 84, or may be made from the side of the tube through an eye-piece carried by the support 88 and that the position of the eye-piece support 88 may be varied through substantially 368 by turning the handwheel 8| and worm 19 to rotate the eyepiece adaptor 82.

The center piece 3|, as previously mentioned, is arranged to be detachably connected to the primary mirror supporting cell. The center piece comprises a cylindrical tube 98 formed of sheet metal and reinforced by structural metallic members, which will now be described. At the inner or left-hand end of the tube 98, as viewed in Fig. 4, there is arranged an inwardly facing circular angle bar 9| having one of its arms welded to the inner surface of the tube 98 and its other arm extending radially inwardly of the tube and in alignment with the end of the same. This radially extending arm of the angle bar 9|, when the center piece and cell are in assembled relationship, bears against the ring 31 and'upon the portion of the sleeve 36 that extends inwardly of the ring for centralizing the cell with respect to the center piece, the angle bar 9| being secured to the ring 31 by means of a series of bolts 92 extending through the ring 31 and the radially extending arm of the bar 9| and into reinforcing plates 93 secured to the inner side of the angle bar 9| and reinforced by bracing members to stiffen the same. Another circular angle bar 94 is arranged within the tube 98 and faces oppositely to the bar 9| and is welded to the inner side of the tube 98 and to the bar 9|, it being noted that the bar 9| and the bar 94 together form a circular channel, thus imparting strength and stiffness to this end of the center piece. Between the opposite ends of the tube 98 there are three circular I-beams 95 spaced longitudinally of the tube and having their outer flanges welded to the inner surface thereof. At the outer end of the tube 98 are two circular angle bars 96 forming a circular channel facing rearwardly of the tube and having their adjacent edges welded together while the arm of the outer angle bar is welded to the inner surface of the tube. Between 8| reinforced by a plate ring |8|a.

the I-beams 88 and the circular channel formed by the angle bars 98 are a plurality of circularly spaced I-beam portions 91 extending longitudinally of the tube 98 and in alignment with one another, all of such I-beams being welded to the inner side of the tube 98 and having the'flanges at their opposite ends shaped to conform with the contour of the I-beams 95 to enable such ends to extend into I-beams 95 and to be welded thereto, see Figs. 4 and 8. The tube 98 is provided at one side thereof and slightly forwardly of its center with a circular opening through which extends the annular skirt 88 of a mounting plate 99 by which the tube is connected to the supporting axes of the telescope. The mounting plate 99 is substantially rectangular in shape and extends from the left-hand I-beam 95 to abut the circular channel formed by the angle bars 96 located at the right-hand end of the center piece, as viewed in Fig. 4, the longitudinal edges of the mounting plate 99 engaging two adjacent longitudinal series of I-beam portions 91 and being welded thereto, the intermediate circular I-beams 95 being cut away to accommodate the mounting plate 99 and skirt 98 and being also welded thereto. The opposite ends of the mounting plate 99 engage with the inside of the left-hand circular I-beam 95, as seen in Fig. 4, and with the inwardly facing channel formed of the angle bars 98, such opposite ends of the mounting plate 99 being welded to this I- beam and this channel. From the foregoing description of the construction of the center piece, it will be clearly seen that the tube 98 with the reinforced I-beams and other structural members referred to, presents an extremely strong and rigid construction for the center piece and that the manner in which the mounting plate 99 is assembled in the center piece and is welded along all of its edges and at other points to the I-beam reinforcement provides a very strong, rigid and lightweight connecting medium, whereby the telescope tube as a whole with the optical system carried thereby may be adequately and efficiently connected to and supported by the supporting axes of the telescope mounting. The axis to which the tube is connected, indicated in dotted lines in Fig. 1 is provided with a finished head fitting within the annular skirt 98 and bearing against the mounting plate 99 such head being provided with a series of circumferentially arranged tapped openings receiving bolts extending through a similar series of openings in the mounting plate 99.

The framework 32, which extends from the center piece outwardly toward the focal point of the primary mirror and which supports the secondary mirror, will now be described. As previously stated, the framework 32 is formed of structural metallic members rigidly interbraced and is detachably connected at its inner or left-' hand end to the center-piece, as viewed in the drawings. This framework comprises a series of circumferentially spaced longitudinally extending I-beams I88, the inner or left-hand ends of which, as viewed in Fig. 4, have welded to their inner flanges a circular inwardly facing channel Each 1- beam I88 has at its left-hand end angle brackets I82 Welded to each side of its web portion and having arms extending laterally of such portion and in radial alignment with the left-hand arm of the circular channel |8|, see Figs. 4, 8, 16, 17 and 18. The left-hand arm of the circular channel |8| lies against and is secured to the base ofthechcularrearwardlyfacingchannelformed ofthe anglebars" ofthecenter piece, bolts I03 passing through suitable reinforcing plates and forming the securing means. Similarly, the angle brackets I02 lie against and are secured to the channel formed by the angle bars by means of bolts I04. Welded to the outer flanges of each of the longitudinally extending III-beams I00, at the left-hand end thereof, are connecting plates I00 which extend beyond the ends of the I-beams and lie against outer surfaces of the tube 00, being secured to the center piece by bolts I00, all of which extend through the tube 80 with certain of thebolts passing through the flanges of the I-beam portions 01 and others of which extend through the outer arm of the channel formed by the angle bars 00, see particularly Fig. I

Before describing in detail the construction of the framework at the outer end thereof where the support for the secondary mirror is arranged, it will be pointed out that the framework is provided intermediate its ends with a number of transverse reinforcing rings. which in this instance are two in number. These rings are made up of I-beam portions I01 extending between ads iacent longitudinal I-beams I00 and being shaped at their opposite ends, as indicated at I08 and 500, seeFigs. 19, 20, 23 and 24, to enable the opposite ends of the I-beam portions I 01 to conform with and to substantially interflt the I- beams I00 so that when they are assembled and welded to the I-beams they will take the form shown in Figs. 19 and 23 and continuous inner flanges will be provided on the rings. At each of the joints between the I-beam portions I07 and the I-beams I00 and located exteriorly of the framework there are arranged reinforcing plates IIO, welded to the I-beams I00 and to the I-beam portions I01. The outer or right-hand ends of the I-beams I00 are interconnected by angular portions III and H2, the latter being arranged at the extreme outer ends of the I-beams I00 and the former being located inwardly of such ends, see Fig. 3.

The angular portions III extend between the I-beams I00 and are in alignment with each other, such angular portions facing toward the outer end of the framework and having their longitudinally extending arms at the opposite ends of the portions shaped and bent inwardly, as indicated at I I3, see Figs. 13,25 and 26, to conform with the contour of the inner flanges of the I-beams I00. The transversely extending arms of the angle portions III at their opposite ends, are cut to conform with the web portion and the inner side of the outer flanges of the I-beams E00, as indicated at Ill. The opposite ends of each of the angle portions III are welded about the inner and outer flanges and to the web portions of the I-beams I00.

The angle portions II2, as previously mentioned overlie the end of the framework and have their transversely extending arms shaped at opposite ends, as indicated at II5, to overlie and cover the outer ends of the I-heams I00, see Figs. 21 and 22, the longitudinally extending arms of the portions II2 being cut away and bent inwardly of the framework to conform with the shape of the inner flanges of the I-beams I00, as indicated at I I 6, providing a continuous flange on the portions II2. It will be understood that the angle portions II2 are welded to the inner .flanges oi the I-beams I00 and to the outer ends of such I-beams and to each other.

In order to give the framework the necessary or additional rigidity and strength where required, a plurality of diagonally extending tie rods III are employed. The tie rods at the inner end of the framework have their ends turned inwardly to lie against the webs of the I-beams I00 and the end of the angle brackets I02, see Figs. 16, 17 and 18, and are welded to such webs and said angle brackets. The ends of the tie rods II! that are connected to the I-beam portions I01 are turned inwardly so as to lie against the webs of the I-beams I00 and the webs of the I-beam portions I01, as well as against the inner sides of the outer flanges of the I- beams I00, such ends of the tie rods I I! being welded to all of said parts of the I-beams I00 and I-beam portions I01, see Figs. 23 and 24. The outer ends of the tie rods II! at the outer end of the framework are turned inwardly soas to lie against the webs and the inner sides of the inner flanges of the I-beams I00 and against the transversely extending arms of the angle portions III, which intumed ends of the tie rods are welded along the portions thereof. contacting with said Ii-beams I00 and said angle portions III, see Figs. 25 and 25.

Adjustably carried by the angle portions III and H2 of the framework are four plates II8 which extend longitudinally of the framework between the said angle portions and project radially inwardly of the framework, the plates II8 being arranged in diametrically opposed pairs. These plates are reinforced and supported at their outer ends by angle strips II9 arranged back to back on opposite sides of the plates I I8 and weld ed thereto with the outer side of their laterally projecting arms lying in the same plane. The angle stripsIIil and the plates II8 are adjustably supported by the angle portions III and H2 by means of threaded sleeves I20 extending through threaded openings in reinforcing plates I2I carried by the angle portions III and H2 and through threaded openings formed in the arms of said angle portions. Bolts I22 extend through openings in the angle strips H9 and through the threaded sleeves I20, the heads of said bolts bearing against the inner side of the angle strips II! and being held in such position by means 'of nuts arranged at the outer ends of the bolts exteriorly of the sleeves I20, see Figs. 6, 12 and 13.

It will be seen that the plates IIO may be adjustod radially of the framework by turning the threaded sleeves I20 and when they have been properly positioned they can be securely clamped in such position by turning or tightening the nuts on the bolts I22 to draw the heads of the bolts tightly against the angle strips H9. The angle strips II9 are provided at their outer ends with angle brackets I23 welded thereto and having a reinforcing plate I24 welded to their laterally extending arms, such arms of the angle brackets I23 and the said plate I24 being provided with threaded openings through which extend adjusting screws I25 by means of which the plates H8 and angle strips II9 may be given slight longitudinal adjustment in the framework, it

' being understood that the ends of the adjusting screws I25 bear against .the angle portion H2 and that there is suflicient clearance between the bolts I22 and the openings therefor through the angle strips Hi! to allow this slight, but necessary, longitudinal adjustment, see Figs. 6 and 12.

The inner ends of the plates I I8 are welded to suitable projections formed on a centrally arranged support I26, which supports the secondary mirror as will hereinafter be described. The support I28 should be of light weight, but possess the necessary strength to support the secondary mirrors and the mechanism associated therewith and for this reason said support is provided with strengthening ribs, as clearly indicated in Figs. 9 and 11. The support I26 is provided with a longitudinal bore and has four openings I21 arranged at diametrically opposite points and intermediate the ends thereof and so located that they will be situated between adjacent supporting plates I I8, see Fig. 9.

It will be seen that since the support I28 is supported by the plates H8 and the latter, together with the angle strips II9, are adjustable both longitudinally and radially of the framework, the support can be accurately positioned and radially supported in the framework in the proper axial alignment with the primary mirror carried by the cell 30. y

As previously mentioned, the secondary mirror may be of either the Cassegrain type or of the Newtonian type. when a Cassegrain type of secondary mirror is used, a mirror mounting such as that shown in Fig. 11 will be employed. This mounting comprises a sleeve I28 suitably reinforced and strengthened by rib portions and having a centrally arranged tubular extension I29 extending from a point located midway between the ends of the sleeve I28 to a point beyond the inner or left-hand end thereof, as viewed'in Fig. 11. The sleeve I28 at its outer or right-hand end, as viewed in Fig. 11, is provided with'a circular flange I30 carrying a plurality of bolts I3l, having a threaded portion, a reduced portion and an exteriorly located knob portion I3I the threaded portions of said bolts being adapted to extend into the threaded openings I32 formed in the outer or right-hand end of the support I26. It will be seen that the sleeve I28 and the parts carried thereby may be inserted in the support I26 from the right-hand end thereof and secured in place by screwing down the bolts I 3| into the threaded openings I32, thus rigidly connecting the sleeve I28 to the support I28.

The secondary mirror of the Cassegrain type, indicated at I33, is carried by a mirror holder and is held in position on a supporting backing I34 forming a part of said holder by means of a retaining ring I35 having an inwardly extending flange engaging with the circumferential edge of the mirror adjacent the concave side thereof and being detachably connected to the backing I 34 by means of suitable attaching screws extending through the ring and into the backing. The backing I34 is provided with a threaded sleeve portion I36 connected to the left-hand end of a tubular member I31 slidably supported in the tubular extension I29 and keyed thereto to prevent relative rotation therebetween. The member I31 at its outer or right-hand end is provided with a centrally arranged nut I38 through which extends an adjusting screw I39 connected through suitable reduction gearing with a motor I40, such motor and reduction gearing being carried by a supporting plate indicated generally at HI and secured to the sleeve I28 in alignment with the tubular extension I29. It will thus be seen that operation of the motor in either the forward or reverse directions will eil'ect inward or outward adjustment of the Cassegrain mirror holder when it is necessary to obtain the correct focal relationship between the primary and secondary mirrors.

When a secondary mirror of the Cassegrain type is being used in the telescope, observations will be made at the rear or left-hand end of the telescope tube (as viewed in the drawings) through either an eye-piece secured to the split collar 84 or an eye-piece carried by the eye-piece support 88, it being remembered that both the collar 84 and support 88 are carried by the eyepiece adaptor 82. When observations are being made from these stations, it will be understood that the light rays enter the telescope tube and are reflected by'the primary mirror 68 to the Cassegrain secondary mirror I33, which then reflects said rays through the center opening I in' the primary mirror and the opening in the circular plate II and thence either directly to the eye-piece carried by the collar 84 or to the prism 89 carried by the eye-piece support 88, from which it is reflected at right angles to the eye-piece carried thereby.

It is often necessary and convenient that observations be made from other stations than the stations just referred to, as for example, that such observations be made from points adjacent to the outer end of the telescope tube. When this condition arises it will be seen that it is merely necessary to loosen the bolts I3I and withdraw the sleeve I 28, together with the Cassegrain mirror and its holder, from the support I26. When this removal of the Cassegrain mirror has been effected, a secondary mirror of the Newtonian type may then be quickly and easily positioned in the support I26.

Referring to Figs. 3, 9 and 10 of the drawings, a supporting construction for the secondary mirror of the Newtonian type will be seen. This construction comprises a cylindrical mirror holder I42 capable of being inserted into the bore of the support I26 from the right-hand end or outer side thereof, asviewed in Fig. 3, and having at its outer end a radially and inwardly offset portion I43. The cylindrical mirror holder I42 is rotatably carried by a stationary sleeve I44 arranged between the offset portion I43 and the support- I26 and having an outwardly extending flange portion I45 through which extend clamping bolts I46 having threaded portions engaging in the threaded openings I32 in the outer end of the support I26, and previously referred to in connection with the support for the Cassegrain type of mirror. The bolts I48 are provided with similar knob portions I3I located at the outer end of the telescope tube to facilitate the assembly of the mirror holder I42 and the sleeve I44 in the support I26. A beveled ring gear H1 is secured to the outer end of the oifset portion I43 of the cylindrical mirror holder I42 and extends over a shoulder on the stationary sleeve I44 and serves to prevent axial movement of the holder I42 in one direction while the annular shoulder, between the offset portion I43 and the remainder of the cylindrical mirror holder I42, engages the inner end of the stationary sleeve I44 and serves to restrict the holder I42 against axial movement in the opposite direction. it being noted that the holder I42 is capable of free rotation within the support I26 by this construction.

The offset portion I43 of the holder I42 is provided centrally thereof with a housing I48 which slidably supports a lock bolt I49 normally urged radially outwardly of the oifset portion I 43 by means of a spring so that the head of the bolt may engage any one of a number of recesses or sockets I50 formed in the stationary sleeve I44, these sockets I50 being illustrated as four in number and arranged at diametrically opposite points on th e inner side of the stationary sleeve, see Figs. 9 and 10. The lock bolt I48 is provided with a camming portion with which engages a camming pin I8I extending at right angles to the lock bolt I43 and centrally of the housing I48. The outer end of the camming pin I5I has a conical portion cooperatlng with a conical 'portion on the end of a rod I82,.which rod projects through an opening in the housing I 48 and at right angles to the camming pin I,

so that when the rod I52 is moved inwardly said rod will retract the lock bolt I43. The rod I52 has slidably keyed thereto a beveled pinion I53 arranged between spaced collars or shoulders on the rod and normally held against the inner of said shoulders by means of a spring engaging the pinion and the outer of said shoulders; The pinion I53 is provided with a shouldered bearing extension arranged to be removably inserted into a bearing opening in the stationary sleeve I44, the shoulder of the bearing extension acting to position the pinion I53 in mesh with the bevel ring gear I41 when the rod and pinion are inserted in said bearing.

It will be noted that the diameter of said bearing is such that the rod I52 and the pinion I53 carried thereby can be readily moved outwardly through the bearing. The rod I52 at its outer end is provided with an enlarged portion having thereon an annular stop or locking shoulder I54 beveled at one side to enable the said shoulder to slide over a spring pressed latch I55 carried by a bearing bracket I56 for the rod when the rod is moved in one direction and to engage against the opposite side of the shoulder I54 when such shoulder has passed the latch and the pinion I53 is in mesh with the gear I41 to prevent outward movement of the rod and disengagement of the pinion, and thereby locking the rod in such position against removal, when such is not desired. The bearing bracket I56 is carried by the angle portion H2 and is provided along one side with a longitudinally extending slot of sufficient width to enable the small portion of the rod I52 to be inserted laterally into the bearing so that the rod may then be moved inwardly until the enlarged portion thereof is within the bearing. Referring to Fig. 6 it will be seen that there are four of these bearing brackets I56 provided on the angle portion H2 and that these bearings are located in radial alignment with the openings I21 in the support I26. The outer end of the rod i52 is provided with a handwheel to facilitate turning the same.

It will be seen that when the rod I52 is in the position shown in Fig. 9 that inward movement of the rod I52 will, through the camming pin i5I, retract the lock bolt I49, it being remembered that the pinion I53 is slidably keyed to the rod I52. After the lock bolt has been so released, turning of the rod- I52 rotates the mirror holder while the lock bolt engages against the inner surface of the stationary sleeve I44, until it is in alignment with the next socket I in the stationary sleeve I44, whereupon the lock bolt will immediately-be projected into the socket and arrest further rotation of the cylindrical mirror holder I42. It will be understood that the rod I52 is allowed to move outwardly after the lock bolt has been retracted and the mirror holder slightly rotated until the latch I engages the shoulder I54. If desired, this operation may be repeated to revolve the mirror holder I42 to its next position or until it reaches the desired position. As soon as the mirror holder I 42 has been rotated to the desiredposition the latch I55 is pulled downwardly and the rod I52 with the pinion I53 thereon moved outwardly until the reduced portion of the rod is within the bearing bracket I58. whereupon the rod and pinion, as a whole, may be removed through the slot in the bearing I56. I

The secondary mirror of the Newtonian type is indicated at I51, such mirror being supportedin a supporting cup I'58 arranged at an angle of 45 to the axis of the support I26 and the rotatable mirror holder I42, the mirror I51 being retained in position by a retaining ring secured to the open edge of the supporting cup I58 and overlying the mirror. The cup I58 is secured in position by means of bolts passing through an internal rib structure forming a part of the mirror holder I42 and into tapped bosses formed on the under side of the supporting cup I58, as clearly indicated in Fig. 9. From the foregoing description it will be noted that the mirror I51 can be moved to diiierent positions so as to face any of the openings I21 of the support I26 and can be locked in such positions by means of the lock bolt I49, previously referred to.

It will be understood that when a secondary mirror of the Newtonian type is used, that observations will be made from points near the outer or right-hand end of the telescope tube, as viewed in Fig. 3, since the rays of light reflected by the primary mirror are reflected by the secondary Newtonian mirror at right angles outwardly of the support I26 and through the openings I21 provided in said support. In order to enable observations to be made at such points the framework is provided with a plurality of supporting plates I59 located between the angle portions I II and I I2 and extending between the adjacent I-bearns I00 and in alignment with the openings in the support I26, such supporting plates I59 being welded at their opposite ends to said I-beams and being of suificient width to support eye-piece adaptors I60 arranged centrally of the plates I 59 and in alignment with the openings I21 in the support I26, see Figs. 3 and 13, the eye-piece adaptors being removed in Fig. 3 and being in position in Fig. 13. Since, in this instance, there are four diametrically opposed openings I21 in the support I26 there are four supporting plates I59 wherefore provision is made for making observations at four different stations adjacent to the outer end of the telescope depending upon the relative position of the Newtonian mirror I51 with respect to the different openings.

In view of the detailed description of the telescope construction, which has been given herein, it will be seen that a telescope tube constructed accordingly has the advantage of being formed of three separate main units formed of structural metal members and possessing lightness while having the requisite rigidity and strength. The primary mirror supporting cell 30 is so formed that the primary mirror can be readily positioned and supported therein prior to the assembly of the cell with the center piece 3I while after such assembly the position of the primary mirror can be accurately adjusted by adjustments made from the outside of the cell. The center piece 3 I, comprising a sheet metal cylinder adequately reinforced and braced by structural metal members integrally welded together, provides the requisite strength for this portion of the telescope tube and enables the mounting plate by which the center piece is connected to the telescope axes to possess the proper degree of strength and rigidity necessary for the accurate support of the telescope tube and the optical system carried thereby. The framework 32 of the telescope tube being formed of structural metal members integrally united by welding has the desired strength and rigidity and is at the same time light in weight. The construction of the framework 32 further provides a strong support for the secondary mirror while the arrangement of the support I26 in the outer end of the framework enables secondary mirrors of various types to be quickly and readily mounted in the telescope tube.

The strength and rigidity of the telescope tube, in addition to its lightness in weight, are of extreme importance since the slightest deflection of the structure would result in rendering the telescope inaccurate and entirely worthless, since it would be impossible to obtain the correct focus. The telescope constructed in accordance with the present invention possesses the still further advantage of the improved and novel mounting for the secondary mirrors and the provision for the adjustment of said secondary mirrors and the detachability of the parts that effect such adjustments. It will be understood that where reference is made to structural metallic members that structural steel, aluminum, duralumin, Monel metal, or other metals or alloys made in the form usual to structural steel" are embraced by such expression.

Although a preferred'form of the invention has been illustrated and described herein, it should be understood that the invention is susceptible of various modifications and adaptations within the scope of the appended claims.

Having thus described my invention, I claim:

1. A telescope tube for supporting the optical system of a telescope which comprises structural metallic members arranged in supporting and reinforcing relationship with one another, said members having portions shaped to mate and interfit with one another and conform to the contour of the tube and integrally united by welding.

2. A telescope tube for supporting the optical system of a telescope which comprises structural metallic members arranged in supporting and reinforcing relationship with one another, said members having portions shaped to mate and interfit with one another and conform to the contour of the tube, and integrally united by welding, certain of said members constituting the supports for the mirror holding and clamping means of the telescope.

3. A telescope tube for supporting the optical system of a telescope which comprises structural metallic members arranged in supporting and reinforcing relationship with one another, said members having portions shaped to mate and interfit with one another and conform to the contour of the tube, and integrally united by welding, certain of said members constituting the supports for the telescope mirror holding and clamping means and for the telescope eye-pieces located at the different observation stations.

4. A telescope tube for supporting the optical system of a telescope comprising a plurality of separate tube units assembled and connected to gether to form the complete tube, each of said units comprising structural metallic members arranged in supporting and reinforcing relationship with one another, said members having portions shaped to mate and interfit with one another and conform to the contour of the tube, and integrally united by welding.

5. A telescope tube for supporting the optical system of a telescope and consisting of a mirror cell unit, a center piece unit, and a framework unit, each of said units comprising structural metallic members arranged in supporting and reinforcing relationship with one another, said members having portions shapedto mate and inter-fit with one another and conform to the contour of the tube and integrally united by weld- 6. In a telescope tube for supporting the optical system of a telescope, a center piece comprising structural metallic members arranged in reinforcing relationship and havingv portions shaped to mate and interfit with one another and conform to the contour of the center piece and integrally united by welding.

'7. In a telescope tube for supporting the optical system of a telescope, a center piece comprising a plurality of longitudinally extending structural metallic members and circularly extending structural metallic members arranged in reinforcing relationship, said members having portions shaped to mate and interfit with one another and conform to the contour of the center piece, and a mounting plate arranged in said center piece and supported by said members, said members and said mounting plate having portions shaped to mate and interfit with each other and integrally united by welding.

8. In a telescope, a cell comprising structural metallic members arranged in reinforcing relationship and having portions shaped to mate and interfit with one another and conform to the contour of the cell and integrally united by welding, and a mirror support carried by said members and including adjustable mirror-positioningmembers.

9. In a telescope tube, a cell comprising struc- I tural metallic members arranged in reinforcing relationship and extending transversely of the tube adjacent an end thereof, said members having portions shaped to mate and interfit with one another and conform to the contour of the cell, and integrally united to each other by welding, and adjustable mirror clamping means supported by said members.

10. In a telescope tube, a cell for supporting part of the optical system of the telescope comprising structural metallic members arranged in reinforcing relationship and having portions shaped to mate and interfit with one another and conform to the contour of the cell and integrally united by welding, certain of said members forming an adjustable support for a part of the 0ptlcal system, and other of said members forming a connecting means between the remainder of said telescope tube and said cell.

11. In a telescope tube, a cell for supporting part of the optical system of a telescope comprising a sleeve and a plurality of structural metallic members arranged in reinforcing relationship with each other and with said sleeve and integrally united to said sleeve by welding, said members having portions shaped to mate and interfit with one another and integrally united by welding, certain of said members forming the support for a part of the optical system and other of said members forming a connecting means between said telescope and the cell.

12. In a telescope tube, a cell comprising structural metallic members arranged in reinforcing relationship and extending transversely of said tube adjacent an end thereof, said members having portions to mate and interflt with one another and integrally united by welding, and an eye piece adapter carried by said members.

13. In a telescope tube, a cell comprising structural metallic members arranged in reinforcing relationship, said members having portions shaped to mate and interflt with one another and integrally united by welding, and countenweights carried by said members.

14. In a telescope tube, a cell comprising structural metallic members arranged in reiniorcing relationship, and certain oi which extend transversely of said tube adjacent an end thereof, said members having portions shaped to mate and interflt with one another and integrally united by welding, an adjustable mirror support carried by said members, and adjustable mirror clamping means supported by said members.

15. In a telescope tube, a cell comprising a sleeve, structural metallic reiniorcingmembers integrally united thereto by welding, said members having portions shaped to mate and interiit with one another integrally united by welding, certain oi. said members extending internally across one end oi! said sleeve, and other of said members being arranged exteriorly of said sleeve adjacent the other end thereof, mirror clamping means, an eye piece adapter, and counterweights carried by said first named members, and a mirror support carried by said sleeve and said last named members.

16. In a telescope, a cell provided with mirror supporting means and mirror clamping means and comprising a sleeve, structural metallic reiniorcing members integrally united thereto, by welding, said members having portions shaped to mate and interflt with one another and integrally united by welding, said members including an attaching and centering ring arranged exteriorly of the sleeve and inwardly of an end thereof.

1'7. In a telescope tubefor supporting the optical system of a telescope, a framework comprising structural metallic members having portions shaped to mate and interfit with one another and integrally united by welding, and plates arranged between certain of said members and adjacent the outer end of said framework and having portions shaped to mate and interflt with said members and integrally united to said members by weld ing, said plates carrying supports for eye pieces to provide for observations at different stations.

18. In a telescope tube for supporting the optical system of the telescope, a framework comprising longitudinally extending structural metallic members, structural metallic members connecting adjacent members of said longitudinally extending members, said connecting members having their opposite ends shaped to mate and interfit with and conform to a portion of the contour of said longitudinal members, and all of said members being integrally united by welding.

19. In a telescope tube, flanged members integrally united by welding, certain of said members being arranged end to end, with other of said members extending angularly between the adjacent ends of said first mentioned members, said first members at such ends being shaped to mate and interfit with the members extending angularly therebetween.

20. In a telescope tube, longitudinally extending structural metallic members having inner and outer flanges, and a reinforcing ring integrally united by welding to said members and comprising flanged members having their ends interfltted between the flanges oi the longitudinally extending members and their flanges oflset and overlying the inner flanges oi the longitudinal members and iorming a continuous flange on said ring.

21. In a telescope tube, means for supporting a primary mirror adjacent one end of the tube, and means for supporting a' secondary mirror adjacent the other end thereof, said last named means comprising a support having a bore, a sleeve carrying said secondary mirror and insertable in the said bore irom the outer end thereof, and means for securing said sleeve in said bore.

22. In a telescope tube, means tor supporting a primary mirror adjacent one end 01 the tube, and means for supporting a secondary mirror adjacent the other end thereof, said last named means comprising a support having a bore extending longitudinally oi the tube, a sleeve carrylng said secondary mirror and having a portion of a size to interfit said bore and being provided at its outer end with a flange, and means for securing said flange to the outer side of said support.

23. In a telescope tube, means for supporting a primary mirror adjacent one end of the tube and means for supporting a secondary mirror adjacent the other end thereof, said last named means comprising a support having a bore, a sleeve insertible in the said bore from the outer end thereof, means for securing said sleeve in said bore, and an adjustable mirror holder associated with said sleeve.

24. In a telescope tube, means for supporting a primary mirror adjacent one end of the tube and means for supporting a secondary mirror adjacent the other end thereof, said last named means comprising a support having a bore extending longitudinally of the tube, a sleeve having a portion of a size to interflt said bore and being provided at its outer end with a flange, means for securing said flange to the outer side of said support, and an adjustable mirror ho1der associated with said sleeve.

25. In a telescope tube which carries the optical system of the telescope, a support, a mirror holder rotatably adjustable in said support, means for moving said mirror holder to different positions, and means for automatically looking the same therein.

26. In a telescope tube which carries the optical system of a telescope, a support, a mirror holder adjustable in said support, means for moving said mirror holder to diiierent positions, means for locking the same therein, and a common controller for both'of said means.

27. In a tube which carries the optical system of a telescope, a support, a mirror holder adjustable in said support, means for moving said mirror holder to different positions of adjustment, means for locking the same therein, a common controller for both of said means and movable in a plurality of directions, the movement in one direction controlling the locking means and the movement in another direction controlling the moving means.

28. In a tube which carries the optical system of a telescope, a support, a mirror holder adjustable in said support, means for moving said mirror holder to different positions, means for locking the same therein, and a common controller for both of said means and capable of both rotative and endwise movement, one of said movements controlling said locking means and the other of said movements controlling said moving means. a

29. In a tube which carries the optical system of a telescope, a support, a mirror holder adjustable in said support, means for moving said mirror holder to diil'erent positions, means for locking the same therein, and a removable common controller for both of said means.

30. In a tube which'carries the optical system of a'telescope, a support, a mirror holder movably mounted therein, means for moving said holder to difierent positions, means for locking the same therein associated with said support and said holder and comprising a bolt carried by the one and recesses arranged'in the other, and a common controller for both of said means and movable in a plurality of directions, the movement thereof in one direction controlling said bolt and the movement thereof in another direction controlling said moving means.

31. In a tube which carries the optical system of a telescope, a support, a mirror holder movably arranged in said support, means including gearing for moving said holder todifferent positions, means for locking said holder in said positions and including a lock bolt, and a common controller for both of said means and capable of endwise and rotative movements and provided with a camming portion and with gearing, the endwise movement of said controller causing the camming portion thereof to control said lock bolt and the rotative movement of said controller causing the gearing thereon to move said mirror holder.

32. In a tube which carries the optical system of a telescope, a support, a mirror holder movably arranged therein and having a gear, and locking means associated therewith to lock the same in different positions, and a removable common controller for controlling the movement of said mirror holder and said locking means and being provided with a camming portion and with gearing removable as a unit therewith.

33. In a tube which carries the optical system of a telescope, a support, a mirror holder movably arranged therein, means for moving said holder, means for locking the same in different positions relative to the support, a common controller for both of said means and capable of endwise and rotative movements, and latching means for retaining said controller in operative *position for its rotative movement.

34. In a tube which carries the optical system of a telescope, a support, a mirror holder movably arranged therein, means for moving said holder relative to said support, means for looking the same therein in different positions, a common controller for both of said means and provided with a portion of reduced diameter, and a bearing for said. controller having a slot through which said reduced portion may be passed transversely of said bearing.

35. In a telescope tube for supporting the optical system of a telescope, a center piece comprising structural metallic reinforcing members having portions shaped to mate and interfit with one another and integrally united by welding, and a sheet metal tube integrally united by welding to said members.

36. In a telescope tube lor supporting the optical system of a telescope, a center piece comprising structural metallic reiniorcing members having portions shaped to mate and interfit with one another and integrally united by welding, and a sheet metal tube surrounding said members and integrally united thereto by welding.

37. In a telescope tube for supporting the optical system of a telescope, a center piece comprising structural metallic members arranged in reenforcing relationship and shaped to conform to the contour of the center piece, and means for securing said members together.

38. In a telescope tube for supporting the optical system of a telescope, a center piece comprising structural metallic members arranged in reenforcing relationship and shaped to conform to the contour of the center piece, means for securing said members together, a mounting plate arranged in said center piece and supported by said members, and means for securing said mounting plate to said members.

39. In a telescope, a cell comprising structural metallic members arranged in reenforcing relationship and shaped to conform to the contour of the cell, means for securing said members together and a mirror support carried by said members.

EDWARD P. BURRELL.

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