This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 Excerpt: ...with a side opening between the eye-piece lenses and a plate of unsilvered glass B (Fig. 122) inclined at 45 to the axis, the following method can be employed: --When a light is placed opposite the opening the rays are reflected by the glass along the axis of the telescope, and if, after they leave the object glass, ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 Excerpt: ...with a side opening between the eye-piece lenses and a plate of unsilvered glass B (Fig. 122) inclined at 45 to the axis, the following method can be employed: --When a light is placed opposite the opening the rays are reflected by the glass along the axis of the telescope, and if, after they leave the object glass, they are reflected back by.a Fio. 122. plane mirror, an image of the cross-wires will be seen alongside the cross-wires themselves. A piece of plate glass is mounted on the table with its sides vertical, and adjusted so that the image of the cross-wires formed by reflection at the surface of the glass coincides with the cross-wires themselves. The telescope is then turned through 180, so that the light is now reflected back into the telescope from the other surface of the glass. If the image of the cross-wires now coincides with the wires, the axis of the telescope is perpendicular to the axis about which the telescope turns. If the image does not coincide with the wires, it must be brought half-way back by adjusting the telescope,1 and half-way by adjusting the table on which the plate glass is supported. This adjustment must, if necessary, be repeated till the image in both positions coincides with the wires. The adjustment will not be absolutely correct unless the two sides of the plate glass are exactly parallel. In general, however, the angle included between the two sides is so small as to produce no material error. If the telescope is not fitted with a Gauss eye-piece, we may assume that the optic axis of the telescope is parallel to the telescope tube, and 1 This adjustment is made by tilting the telescope about a horizontal axis with reference to the movable arm which carries the telescope. The arrangements for making this adjustment var..
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Seller's Description:
This book has hardback covers. Ex-library, With usual stamps and markings, In poor condition, suitable as a reading copy. No dust jacket. Please note the Image in this listing is a stock photo and may not match the covers of the actual item, 900grams, ISBN:
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Seller's Description:
This is an ex-library book and may have the usual library/used-book markings inside. This book has hardback covers. In good all round condition. No dust jacket. Please note the Image in this listing is a stock photo and may not match the covers of the actual item, 1000grams, ISBN:
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Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
