. The American journal of science and arts. mined, will give the value of the angle sought. Now theonly difficulty lies in detecting ejMaZ degrees of intfenseness. ThisI have tested both by the amount of a double right angle, and byaffixing an angled plate upon the revolving plane. It can be doneby simply catching the darkenings on the edges, as they approach theaxis of the planes the value of whose angles is sought. Thereare two kinds that have been used. One made of brass with bandsand braces instead of being solid, is an expensive though light andpretty instrument. The other is made of tvel
. The American journal of science and arts. mined, will give the value of the angle sought. Now theonly difficulty lies in detecting ejMaZ degrees of intfenseness. ThisI have tested both by the amount of a double right angle, and byaffixing an angled plate upon the revolving plane. It can be doneby simply catching the darkenings on the edges, as they approach theaxis of the planes the value of whose angles is sought. Thereare two kinds that have been used. One made of brass with bandsand braces instead of being solid, is an expensive though light andpretty instrument. The other is made of tvell seasoned wood ; It Isless neat in appearance, but is simple, cheap and can be made by al-most any person, (I made the one I use myself.) It Is the latterInstrument that I shall describe. Elevation view.—The dark concentric ring AA, bounding II, ismade of mahogany one half or three fourths of an inch in breadthupon the anterior surface, two inches deep till it meets II, it is then 76 Reflective Goniometer. BEFLECTIVE GONTOMETEK. Fig. InchesScale of one foot. continued beneath I-I, posteriorly one inch deep to the center squarebolt N. A vernier or nonius DD, of silvered brass is attached toAA, hall way up anteriorly, graduated in minutes corresponding to Reflective Goniometer. 77 tlie degrees upon BB ; and for the better concentration of the visualrays a small knee K, is made to lit upon the line of O on the ver-nier at the angle of vision K. The plane II (of maple or any light colored wood) is made to fitthe innc}- part of A, both surfaces I and A being in the same planeanteriorly, one inch in depth and seventeen inches in diameter. Itrevolves upon the iron axis Z, and has a small brass head piece E,attached to it (and revolving with it) from the center, p, of which isa pin- projecting three fourths of inch from its surface, upon whichthe crystalline form that we wish to inspect is adjusted and semi-circular band of brass BB, three fourths of an inch wide isfa
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Keywords: ., bo, bookcentury1800, bookpublishernewhavensconverse, bookyear1820
