A treatise on architecture and building construction (1899)
International Correspondence Schools · Scranton, The Colliery engineer co. · leaf 195
J 0 7 88 Fig. 95. candle a. The observer looks down through the tube e intomirrors y and ^, and thus sees the reflection of both sides of 164 PLUMBING AND GAS-FITTING. 16 the diaphragm at the same time. If they appear of unequalbrilhancy, the sight-box d is moved along the bar Ji until theybecome… … Fig. 359. There are two methods of constructing the dia-phragm in vogue. Tlie spot diaphragm is shown in Fig. 96. The center a is a. disk of opaque whitepaper. The ring b is made of whitepaper which is saturated with paraffin,and is translucent. The outer part c isblackened. When this diaphragm…
Architecture · Building
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