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C. 1-28 BEKGEU & SONS. Monitor Type Dumpy Level. Additional Information pertaining to its mechanical Construction. From the illustrations, pages 127, 129, it will be seen that the mechanical parts of this Dumpy Level are few and can easily be made to be mechanically correct, and that there are no working strains whatever in the metal to exert an undue influence upon the adjustments with changes of temperature. The telescope barrel and both uprights are cast in one piece of hard composition metal; and in order to arrive at a high degree of accuracy the barrel is bored out to be truly cylindrical, a condition never attained by the use of drawn tube. (For reasons mentioned later both ends of the outside tube are slightly larger in diameter, forming collars turned truly concentric to the bore, serving in principle the same object as collars of a Wye Level telescope.) This being accomplished, the bottom surface of the uprights is turned truly parallel to the bore. The strongly-ribbed cross-bar and instrument center are cast in one piece of hard bell-metal. At the time when the center about which the instrument revolves is fitted to its socket, the resting-places for the uprights are also turned off so as to be truly at right angles to it, from which follows that the geometrical axis of the telescope barrel when latter is placed upon them must also be at right angles to the center. The level casing, too, is a casting. The spirit-level itself is fastened into this casing by a superior method to preclude any strain, so that its true form may "be preserved, The focusing slide is the only tube made of brass, turned and closely fitted in the lathe. In adjusting this instrument in the shop it is treated like a Wye Level. The collars at the end of the telescope barrel serve to adjust the cross-wires for collimation by revolving the telescope in wyes. When this is accomplished the telescope barrel with its attached level is then firmly screwed to the cross-bar. The next step in the shop is to adjust the spiritlevel to the line of collimation as described elsewhere. This being done, the adjuster in the shop now proves whether the geometric and optical axes of the telescope are really in the horizontal plane by revolving the instrument 180 on its center; should the bubble remain in the middle of its tube it must be assumed that it is; however, if not, he touches one of the uprights off until it does. As a rule the mechanical work is so correct that the geometric and optic axes coincide within a few division marks of the graduated level, requiring but a very few strokes with a fine file for final adjustment. From the foregoing it will be seen that a leveling instrument so constructed, barring severe accidents, must hold its adjustments for years, and that all subsequent verifications of the line of collimation in the field by the two peg method must be made by the Engineer by slightly moving the cross-wires, and that the adjustment of the spirit-level is to be made in the customary manner by simply turning the instrument 180 on its center. An instrument so constructed needs but little care and therefore is better adapted to rough usage (to which it is subject at times) since its simplicity ensures greater freedom from derangement. The Dumpy Level described above must stand as an example of good practice. Many Engineers prefer it to an ordinary Wye Level. The prevailing mistrust can generally be traced to the use of cheap commercial Dumpy Levels. The above information as to the method of construction in the shop has been given at great detail tr eho\v that this instrument may well rank with the best wye levels. (For Price of this <strong>Instrument</strong> and Extras see page 126.) Berber's Collapsible Dust Guard This feature as shown below is furnished with the 14, lo and 1 7>2 inch 3Ioiiitor Type Dumpy Levels and protects the telescope's focussing slides almost completely from grit and water within their entire range. TELESCOPE BARREL- C.L.BE.RGERiSON3 BOSTON MA5S.U.5.A. EXTENDED CONTRACTED
-inch erecting telescope 129 C. L,. BEIIGKR & SONS, Code AVorcls for Dumpy Levels. -inch erecting telescope with fixed stadia wires . (For Extras and changes from Acnia and Actus see page B of complete code at back.) Aciiia Actus
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ENGIN. LIBRARY UC-NRLF STANDARD INS
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PREFACE. THE instruments enumerated
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DESCRIPTION OP THE Essential Featur
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Tangent Screws. These are made of A
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The Finish. It is a well-known fact
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11 whatever. As a rule more harm th
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13 has sufficiently developed to im
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15 ordinary instruments, but it mus
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17 frame, and apply another drop of
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19 The finer and finest classes of
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21 applied with an adjusting pin ab
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23 adjustment of the telescope in t
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25 Owing to the many improvements m
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27 Engineers 9 Instruments and Thei
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ITrfpodfead 2 // Bolt 3 // >/ Mf J
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In practice, however, many engineer
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34 The Pancratic, or Changeable Pow
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the 130 division, and moved on unti
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38 Graduation Reading to 2O". A 15
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Decimal Vernier Graduation. For rai
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HORIZONTAL CIRCLE HORIZONTAL CIRCLE
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44 line of collimation of the teles
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46 Obviously then, the number of wh
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48 Gradienter Screw Table I. Factor
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50 The subjoined table affords a re
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52 Plumbing and Centering Arrangeme
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54 To make the adjustment for Paral
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56 capstan-headed screw at left to
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58 To adjust the line of collimatio
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62 The Adjustment of the Wye Level.
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On slightly rising ground locate fo
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(5.) Astronomical Triangle. The hei
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68 From the -(- sign of the " diffe
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70 Degree of Precision Required. (1
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72 tions for refraction, using the
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74 Correction to the Mean Refractio
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76 Table H. Coefficients showing th
Page 84 and 85: 78 To Find the Meridian from " Pola
Page 86 and 87: 80 REMARKS. If the instrument is no
Page 88 and 89: 82 These devices are being more and
Page 90 and 91: 84 c. Directions. For finding the S
Page 92 and 93: 6. Directions. For reducing the nor
Page 94 and 95: 88 On Stadia Measurement. Written e
Page 96 and 97: 90 included between this and the ot
Page 98 and 99: 92 Jug, R, of the rod AB is the dif
Page 100 and 101: 94 gent screw of the main telescope
Page 102 and 103: 96 zero when plates are leveled up
Page 104 and 105: i I * 2 I! all 35 e 5c u fcc - = H
Page 106 and 107: 100 Berger Short Focus Lenses. A se
Page 108 and 109: 102 NOTE. In selecting instruments
Page 110: RIBBING PARTS OF INSTRUMENTS. Patro
Page 115: The Berber Complete Engineers' and
Page 119: [Patented) The Berber Complete Mine
Page 122 and 123: 11(5 5 O o to tO u tO CM in in in o
Page 124 and 125: 118 n ai in Spirit Levels. For the
Page 126 and 127: l, 33 120
Page 128 and 129: 122
Page 130 and 131: 14 124 C. L,. BEKGEK & SONS. BOSTON
Page 132 and 133: 1 5" AND 1 7|" C. t. BKKGER & SONS.
Page 136 and 137: 130 The Berger 18 MONITOR TYPE WYE
Page 138 and 139: 1 18 132 C. I*. BERGER & SONS, BOST
Page 140 and 141: 18 134 II ENGINEERS' WYE LEVEL. lev
Page 142 and 143: 136 18" HYDROGRAPHER'S WYE LEVEL Ha
Page 144 and 145: 138 Reversion Level. Applicable to
Page 146 and 147: 140 The Telescope will be invariabl
Page 148 and 149: 142 THE GEODETIC LEVEL. In response
Page 150 and 151: 144 COAST SURVEY PRECISE LEVEL The
Page 152 and 153: 146 PLANE TABLE This instrument, as
Page 154 and 155: 61" 150 ENGINEERS' AND SURVEYORS' T
Page 156 and 157: No. 1 a. 6 1 4 in. at edge of gradu
Page 158 and 159: No. I a. T 4 in. at edge of graduat
Page 160 and 161: No. 1 c. 154 C. L. BERGER & SO>S in
Page 162 and 163: No. 1 c, Style p. in. at edge of jr
Page 164 and 165: . 1 f. is made by C. L. Berger & So
Page 166 and 167: 160 C. L. BEKGEK & SONS. MONITOR TY
Page 168 and 169: 162 64 SURVEYORS' TRANSIT No. 1 s.
Page 170 and 171: 5^" 164 C. L. BERGER & SONS, BOSTON
Page 172 and 173: 166 C. L. BERGER & SONS. BOSTON 5|"
Page 174 and 175: 5|" 168 ENGINEERS' AND SURVEYORS' T
Page 176 and 177: The Surveyors' Solar Attachment. Pl
Page 178 and 179: 172 The Berger Solar Attachment Att
Page 180 and 181: 174 Davis' Patent Solar Attachment.
Page 182 and 183: 176 THE 5|" MOUNTAIN TRANSIT. This
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178 The 41" Mountain and Mining: Tr
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4|" 180 C. L,. BERGER & SONS. BOSTO
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182 The 4" Mountain, Mining and Rec
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184 The 4" Complete Transit- Theodo
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186 4>4 " Complete Mine Transit No.
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^ 188 t4 Mining Transits. All of th
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The 190 See M Fig. 1. Berger Patent
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03 192 Complete Mining Transit No.
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|S go Complete Wet-Mine Transit No.
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196 Different Types of Vertical Arc
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:i98 Edge G-racl nation for Vertica
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The Open-Frame Protected Vertical C
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202 C. L. BEKGKK & SONS. Flexible J
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S fa 204 Style of trivets used with
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200 Patented. The Lateral Adjuster
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Mining Transit. Interchangeable wit
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210 Tunnel Transits. Xo. 1C a Tunne
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212 Triaiigulatioii Transit- Theodo
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No. lib. 214 Complete Double Opposi
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210 No. 11 m. 7-iiich Complete Tran
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218 No. llg, 7-inch Complete Triang
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220 No. 12. 8-iiich Transit for Tri
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SPECIFICATIONS : No. 15 Alt-Azimuth
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No. 15 b. Alt.-Azimuth. 224 Alt. -A
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Portable Transit Instrument for Lat
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228 Reflecting Circle. Artificial H
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230 Current Meters, The types of cu
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232 Current Meters No. V and VI, As
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234 Plain Polar Plaiiimeter. This P
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236 Leveling Rods No. 145 No. 147 N
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Paine's Steel Tape Measures. & inch
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240 Surveyors' Chain Tapes. Heavy J
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2-12 Standard Steel Tape Measures.
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No. 210. Plummet Lamp. tfo. 212. 24
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246 Portable Anemometers. These ins
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PRICES SUBJECT TO CHANGE WITHOUT NO
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J Tripod Head 2 // Bolt 3 * .* Nut
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Levels, Locke's Hand Reversion Revo
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C. Li. Berger & Sons' Bevel-Limb Tr
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0) O (^ c CL 0? Z O (0 O K lu ffi C
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O CO K III III These prices do not
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ord (In whether . 4 O ~ bJD p,"* 3,
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a -iQ. Q u u o 0) o 0) U O U CO o C
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These prices do not include bag (SI
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Q III o o z o u o o U Ott bl CD O U
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o O (0 ui y O J O Q. O U 5> OC os .
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800290 I A 33012 Engineeringlibrary
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