1884.] 



MICROSCOriCAL JOURNAL. 



A very simple and in all respects 

 satisfactory indicator is made by at- 

 taching a hair to the diaphragm of an 

 ocular, so that it will extend halfway 

 across the field of view. This is eas- 

 ily done by selecting a small bit of 

 paper, placing a little gum upon it, 

 and laying a hair across it, the point- 

 ed end of the hair extending just far 

 enough beyond the paper. When 

 dry cut the paper to a proper size 

 and moisten the gummed side. Then 

 place it in position on the diaphragm 

 of the ocular, let it dry, and the ap- 

 paratus is ready for use. This simple 

 arrangement is entirely satisfactory, 

 and we have it now in constant use. 

 The hair is not objectionable in the 

 ocular, as it appears like a fine, sharp 

 line, and is quite overlooked when 

 one gets accustomed to its presence. 



The Improved " Biological" Stand. 



Mr. Bulloch has made further im- 

 provements on his " biological" mi- 

 croscope that deserve complimentary 

 notice. The principal improvement 

 relates to the substage, which at first 

 did not impress us favorably, but hav- 

 ing since found opportunity to test it 

 practically, w^e would give it unquali- 

 fied commendation. 



The substage and mirror-bars move 

 independently, with the object as a 

 centre, as heretofore, but immediately 

 beneath the stage, just above where 

 the rack-work ends, the substage-bar 

 is cut transversely and the two parts 

 joined together by a pinion and screw 

 passing vertically through lateral pro- 

 jections cast for the purpose. About 

 this pin the lower part, carrying the 

 substage with its rack and centering 

 screws, swings laterally, entirely out 

 from beneath the stage. The space 

 between stage and mirror is thus en- 

 tirely clear, and this is a much better 

 plan than the one adopted by some 

 English makers, who remove the sub- 

 stage entirely, which we have spoken 

 highly of in a previous article. For not 

 only is the space before mentioned 



unobstructed by the substage, but the 

 substage itself is practically clear of 

 the microscope, where it can be seen 

 and apparatus removed from it or 

 added to it with even more facility 

 than if it were held in the hand. 



We are not aware that this plan of 

 removing the substage has ever been 

 applied to a microscope before. If 

 not, Mr. Bulloch deserves great praise 

 for it. He has not said one word 

 about it to us, and it may be that he 

 is not himself fully aware of the great 

 convenience of the device to the work- 

 ing microscopist. We regard it as 

 the greatest improvement in substage 

 fitting that has been made in years, 

 and one that is sure to be appreciated 

 as its value becomes known. 



The substage ring is also made in 

 two parts, and the lower part swings 

 to one side independently. This part 

 may carry a tinted glass to modify the 

 light, or the diaphragms of a con- 

 denser, which could be conveniently 

 changed. We would suggest, how- 

 ever, that it would be better to place 

 the condenser and its diaphragms in 

 the upper substage-i'ing, while the 

 polarizer with its plates of mica and 

 selenite are fitted in the lower ring. 

 Such an arrangement would give the 

 microscopist every facility tor work 

 that could be desired. Without re- 

 moving a single accessory he would 

 be prepared to use the light directly 

 from the mirror, by turning the sub- 

 stage aside. Then the condenser 

 could be brought into use by a single 

 motion, and the difierent effects of 

 oblique light and dark-ground illumi- 

 nation obtained by the simplest pos- 

 sible operation of changing dia- 

 phragms. Then by throwing in the 

 polarizer, whicli is always ready for 

 use, all the effects of polarized light — 

 which are almost inexhaustible — can 

 be obtained. 



With this substage even a better 

 system of substage illumination is 

 possible than is afibrded by Swift's 

 condenser, which we have already so 

 highly commended. It only remains 

 to properly arrange the illuminating 



