On a new case of the interference of light / by the Rev. Baden Powell.

  • Baden Powell
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: On a new case of the interference of light / by the Rev. Baden Powell. Source: Wellcome Collection.

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    (39.) Glass and Water, r=’0]5 inch. Ray. r-p- tPp—fPm X Diff. = n. Remarks. B. D. F. G. H. 1-526 1-529 1-536 1-542 1-546 1-331 1-333 1-337 1-341 1-344 + 195 + 196 + 199 + 201 + 202 + 7672 + 9009 + 11092 + 12663 + 13796 + 115 + 135 + 166 + 190 + 207 + 20 + 31 + 24 + 17 Hence arrangement II. will give bands. + 92 (40.) Calc-spar and Oil of Cassia, ordinary ray. Rudberg’s indices. Ray. f^po- /Pp — fPm- f^p—fPm t=04. DilF. Remarks. B. D. 1-6531 1-6585 1-5945 1-6073 + -0586 + -0512 + 2306 + 2353 + 92 + 94 + 2 Hence with arrange- ment I. there will be no bands from B to D, but bands from D to H. F. G. H. 1-6680 1-6762 1-6833 1-6358 1-6671 1-7025 + -0322 + -0091 -•0192 + 1794 + 573 + 1311 + 71 + 23 -52 - 23 - 48 - 75 146 (41.) For the extraordinary ray, in a plate bounded by the planes of cleavage, Mr. Stokes has calculated the results as follows:— “ The incidence is supposed to be perpendicular; that is, strictly, the rays B, D, &c. are supposed to be received in succession at a perpendicular incidence: but the results may be applied with very little error to the case in which rays of mean refran- gibility are incident perpendicularly. “ The dihedral angle of the rhombohedron of calc-spar is 105° 5'*. “ If i be the inclination of the axis to the normal of the plate, we get by a spherical triangle, sin i= cos 52° 32'5 cosec 60° whence i=44° 36''6. Now:|' we have v=\/od- cos^ i-\-c^ sin^ i=a cos i sec 6 , . • J“'^o where tan 6=- tan ^=— tan and if id ^ sec i cos 0. Also log tan i=9'99409, and log sec i=10T4758. Hence log tan 0= log|M/'o— log|!>!,'g-i-9'99409 log|M;'= logjU/'o-p log cos ^-1-10‘14758 —20. * Phillips’s Mineralogy. t Airy’s Tract, Art. 151.
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