450 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the Microscope. The directly found value of the z co-ordinates is the 

 true one, only when object and objective are in the same medium in 

 any other case the directly found value must be multiplied by the r;t o 

 of the refrac ive indices of the media. The co-ordinate's of the^six points 



^Iting^SsT' ^'^ ^""'^^^^^^ ^^ "^^ --* ^--^1 -- '^ "- 



« = ^2^3 - y^z^ + ysZy- y,z, +y,z,- y.^z, ■ 



b = XsZ^- X.,Z, -{-X,Zs- X,Z, + X,Zi - x,z,- 



c = x,y, - xsy, + xstj, - x,y^ + x,y,~ x,y, ; 

 «i = y,z,- y,z, + y,z^- y^z, + y,z,- y,z,\ 



\ = X,Z,- X,Z, + X,Z,- X, Z, + X,Z,- X, z, ; 



and ""' " '^'^' -^ey, + x,y, - x,y, + x,y,- x,y,; 

 cos A = (^ai + hh,^+^cc^ 



i«YeiVrntn^P^/V'^°^''*''^^"*}^'* *^" instrument described above 

 1. ve y convenient for measuring plane angles. This is simply effected 

 by successively bringing the long side of the scale into coincklerce with 



Handdmgen v. h. I. Mrl Aahmr- en Gmeeskund. Congrcs te Amsterdam. 



Engl, ilech., XLIX. (18S9) p. 196 (1 fig.). 

 (4) Photomicrography. 



Moeller's Photomicrographic Apparatus.* — Dr. H Mopllpr'« 

 camera (fig 68) is similar to"^ the one suggested by HattincTwith ' ^ 

 bellows, and with which the eye-piece is usS. I? differs from' ilhovv 

 ever, m being fixed directly to the Microscope witW any sTand of^s" 



oTthe ctet^ ttetttf ^^J'^^T* 'f ^^' ^^ totpTo^tte' tfgh 

 It consSrof ;t^,! IS ."^"''^ T'^^ ^' i^S^* ^' P«««ible. To this end 

 " consists ot a tour-sided wooden frame, of the shape shown in the fie 

 covered with light-Droof dart olnih a\ +i, ^ i'*', bnuwii m ine ng., 



slides ovpr th^Zl • ? • . * *^® ^"^^^' ^"^ IS a socket which 



whth vl!f 1 T"^'^?' ^""^ «'^"'i«« ^^ its upper part a diaphragm disc 

 which rests closely on the upper surface of the eye-piece foriSns t hi s 

 he point of support for the camera and a light-proof conncctTon^ For 



on the micrometer screw ^ ^"^ ^^^^ ^° injurious effect 



* Zeitsohr. f. Wiss. Mikr., v. (18SS) pp. 155-65 (1 fig.). 



