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RECORD OF CURRENT RESEARCHES RELATING TO 



also carries an adapter (j for the reception of objective, having the 

 standard screw, so that any suitable objective can be used as a 

 condenser. 



But in taking angles with the candle-radiant in use, a tube i, of 



A, grooved semicircular plate, h, traverse-lens fitted to stage c. c, stage on 

 which the object is clamped, d, condensing lens fitting on k. F, elbow-arm 

 for attachment of the whole apparatus to the substage of the Microscope. Tliis 

 attachment is effected by means of an adapter y, or can be fitted with rack move- 

 ment, g, an adapter for auxiliary tube, or to carry an objective as a condenser. 

 h, a plate on which is mounted various apparatus for directing and condensing 

 light upon the object, i, auxiliary tube for measuring apertures, k, a solid 

 glass cone, concave at the smaller end (for immersion contact with the traverse- 

 lens U) and plane at the other, upon which a condensing lens d fits, or the semi- 

 circular diaphragm z. m, a rectangular prism, to give direction to the light 

 axially upon k or n. n, a reflecting prism (acting with two internal reflections), 

 to give very great obliquity of the illuminating ray with moderate movement of 

 the plate /t out of the axial position, or the zero position, o, a hemispherical 

 traverse-lens, for use in measuring the widest possible interior angles, with inter- 

 vening medium of index 1 '525 ; it fits in the position occupied by h and c in the 

 figure. /', a radial arm extending from the plate /;. p', arm for candle fitting iu 

 tube t. b, c, k, m, n, and j), are removable. 



