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    "localId": "7077466",
    "label": "Sky and Telescope Magazine",
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    "citationUrl": "https://catalog.archives.gov/id/7077466"
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    "id": "7077466",
    "sourceUrl": "https://catalog.archives.gov/id/7077466",
    "contentType": "document",
    "title": "Sky and Telescope Magazine",
    "description": "This item contains volume seven, issue three, number seventy-five of Sky and Telescope Magazine.",
    "citationUrl": "https://catalog.archives.gov/id/7077466",
    "collections": [
        "Russell W. Porter Papers",
        "Publications"
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    "url": "https://catalog.archives.gov/id/7077466",
    "naId": 7077466,
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    "productionDates": [
        {
            "logicalDate": "1948-01-01",
            "month": 1,
            "year": 1948
        }
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{
    "seq": 8,
    "pageIndex": 0,
    "type": "photo",
    "url": "https://s3.amazonaws.com/NARAprodstorage/opastorage/live/66/774/7077466/content/arcmedia/dc-metro/XRWP/gallery/hd1-111196098-2012-019-pr.jpg",
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    "ocrText": "GLEANINGS FOR A. T. M.s\nEDITED BY EARLE B. BROWN\nA FEW INSTRUMENTS BUILT BY AMATEURS\npower of better than three seconds of arc\nis obtained. That's a lot for a $4.50 lens!\nR\nOY A. RENNER, of Grant's Pass,\nDeclination axes: These were made from\nAt present the telescope is used daily\nOre. (now T/5 Renner), writes of his\nModel A Ford \"wishbones.\" The balls are\ninstrument, which was constructed by him\nwelded onto the telescope tube band, and\nand his father, as follows:\nthey fit in their sockets, which, with adapt-\nMirror: 6\" plate glass - 1\" thick; good\ner couplings, are welded to the ends of\nMAKING\nfigure, aluminized.\nthe fork. The arms of the wishbones are\nYOUR OWN\nMount: fork-type, semiportable. Fork\nthe tripod legs.\nis of welded steel I-beam and channel sec-\nBearings: The polar axis works on roller\nTELESCOPE\ntion, welded to a truck front-wheel hub\nbearings, and has no play. The declination\nspindle, and this in turn welded to a heavy\nbearings may be adjusted for proper fric-\nBy ALLYN J. THOMPSON\ntion to hold the tube in any desired posi-\ntion.\nStory of the Telescope\nT/5 Roy A. Renner - 19277059\nMaterials and Equipment\n892nd Ordnance HAM Co.\nMirror Grinding\nAPO 901, c/o Postmaster\nThe Pitch Lap\nolishing-Testing-Correcting\nSan Francisco, Calif.\nThe Paraboloid\nThe Diagonal\nEdward Olson describes his f/5.4 re-\nTube Parts-Alignment-The Finder\nfractor:\nEyepieces and Related Problems\nThe objective is of 21/4\" diameter, and\nThe Mounting\nhas a focal length of nearly 121/4 inches.\nAluminizing and Cleaning\nIt is fluoride coated. I turned up a cell\nSetting Circles-Equatorial Adjust-\nment\nout of wood, provided for collimation, and\nOptical Principles - Atmosphere -\nfind such a cell entirely suitable for small\nMagnitudes\nlenses. The tube is of heavy cardboard,\nA Second Telescope\nwell painted, and mounted on a saddle\nSecondary Reflections; Making an\nsimilar to the one on Hans Pfleumer's\nOptical Flat; Bibliography.\ntelescope (see Sky and Telescope, August,\n1947); the mount, however, is of the alt-\n2II pages, 104 illustrations\nPrice $3.50\nazimuth type. I use four eyepieces, from\n9.6x to 49x.\n(Remit foreign orders in American funds,\nplus 25 cents mailing costs.)\nThe performance of the instrument has\nbeen gratifying. Definition is fine right up\nSKY PUBLISHING CORPORATION\nto the highest power, and a resolving\nCambridge 38, Mass.\nASTRONOMICAL OBJECTIVES\nE CAN SHIP FROM STOCK quality astronomical\nobjectives with the following features:\n1. Superior optical design utilizing a larger air separation.\nColor corrected on C and F and hand corrected on spac-\ning to reduce residuals to a minimum. Completely freed\nRoy Renner's fork-type mounting and\nof coma.\nreflecting telescope.\n2. Glass-air surfaces magnesium fluoride coated increasing\nlight transmission approximately 10 per cent.\nflywheel, which includes the starter ring\n3. Quality optical glass precision annealed and held to\ngear. It is intended later to use this with\none ring test plate match.\na suitable worm for a slow-motion drive.\n4.\nCell made to precision tolerances and suitably coated to\nMirror cell and mounting: The mirror\nprevent stray light reflections. Each cell engraved with\neffective focal length and serial number.\ncell is a short length of 6\" pipe with a\nThese objectives are supplied as follows:\n1\" welded back-plate, with holes drilled\n3\" C.A.\n45\" E.F.L.\n$ 62.00\nfor ventilation. The cell is threaded into\n4\" C.A.\n60\" E.F.L.\n138.00\na coupling, upon which is shrunk a nar-\n6\" C.A.\n90\" E.F.L.\n484.00\nrow external band. The telescope tube, of\nThese objectives are sold with cells and rigidly tested\non star diffraction patterns and resolving power before\n20-gauge sheet metal, is surrounded by a\nbeing sold.\nwide steel band upon which the declina-\ntion axes are welded. A short length of\nORTHOSCOPIC OCULARS\npipe in front of the mirror cell slides inside\nthe tube, and the external band fits against\nW\nE HAVE IN STOCK for immediate delivery the\nthe wide band on the telescope tube, thus\nbest eyepiece ever produced for astronomical\nand scientific work with these characteristics:\nproviding a position lock which permits re-\n1. Four-element design giving a flat, beautifully corrected\nmoving and replacing the mirror without\nfield of 50° covering more than 160 per cent of the area\nlosing collimation. The steel band around\nof the conventional Ramsden for the same power. This\nthe tube provides sufficient weight, to-\neyepiece is a \"must\" for RFT work.\n2. Precision optical elements, magnesium fluoride coated\ngether with the cell mounting, to bring the\nincreasing the light transmission approximately 10\ncenter of gravity near the rear end of the\nper cent.\n3. Simple take-down for cleaning.\ninstrument.\n4. Precision metal parts black anodized for anti-reflection\nand ground to 11/4 inches outside diameter.\nGLEANINGS is always ready to re-\n5. Clean mechanical design permitting comfortable observa-\ntion and ease of focusing.\nWe Guarantee Complete Satisfaction\nThese eyepieces are produced in 16mm. and 32mm.\nor Money Refunded.\nceive reports and pictures of amateur\ninstruments and devices, and is open\neffective focal length only.\nPrice postpaid, $9.85 each\nIMMEDIATE DELIVERY\nfor comments, contributions, and ques-\nBRANDON SCIENTIFIC DEVELOPMENT\nP. o. BOX 85\nMALVERNE, N. Y.\ntions from readers.\nJanuary, 1948, SKY AND TELESCOPE\n75"
}