1883.] 



MICROSCOPICAL JOURNAL. 



187 



botanists, nor all zoologists, nor all 

 students of lithoiogy, yet we have a 

 well defined common ground. We 

 are all deeply interested in the physics 

 of the microscope, and in the methods 

 of its use, and in order to be skillful 

 in that department of investigation 

 that we have severally chosen, we 

 must be, more or less, fully practical 

 in microscopic work in many other 

 fields." After showing the necessity 

 for verification, the several methods 

 were discussed under the following 

 heads : repetition of observation, the 

 use of the camera lucida, photomicro- 

 graphy, media and re-agents, im- 

 proved lenses and accessories, and a 

 better knowledge of optics. In 

 closing the address he said, "Let us 

 resolve to use this wonderful agent of 

 investigation more earnestly, with 

 greater carefulness against error and 

 reverence for the truth, and so s^^ek 

 more and more to kno\v things as 

 they are, and as we shall know them 

 some day, I trust, when we shall no 

 longer see through a glass, darkly ; 

 but shall know even as we are 

 known." 



The forenoon session of Wednes- 

 day was mostly occupied with reading 

 and discussing papers on Bacteria. 

 Prof. T. J. Burrill gave at length 

 Methods for Preparing and Mounting 

 Bacteria. Dr. H. J. Detmers pre- 

 sented a discourse upon Pathogenic 

 Bacteria, followed by one by Dr. Geo. 

 E. Fell, on the Clinical Effects of 

 Ozone on the Micro-organisms of In- 

 fusions. It is impossible to give the 

 gist of these papers in a few words. 

 The animated and learned discussions 

 which followed, demonstrated the 

 value of the papers, and the fact that 

 our investigators are awake to the 

 importance of a knowledge of these 

 forms. 



The first paper of the afternoon 

 session was a masterly discussion of 

 the Action of a Diamond in Ruling 

 Lines on Glass. At the outset the au- 

 thor paid this high compliment to a 

 contemporary : '" In offering this com- 

 munication upon the subject indicated 



by the title of this paper, I am not 

 unmindful of the fact that I enter a 

 field in which I acknowledge a master. 

 Since the death of the incomparable 

 Nobert, Mr. Fasoldt of Albany stands 

 easily first in the art of fine ruling. 

 . . . I have thought it better to con- 

 fine my attention to another equally 

 important problem, viz. : an attempt 

 to obtain correct copies of the Impe- 

 rial Yard and Meter des Archives, at 

 the temperature at which they are 

 standard, to sub-divide these units into 

 aliquot parts, and thus to obtain a 

 microscopic unit whose sub-divisions 

 should be so nearly equal that the 

 microscope would fail to reveal the 

 difference. The first part of this 

 work has been nearly completed. . . . 

 The sub-division of these units into 

 aliquot parts — the yard into inches 

 and the meter into centimeters — has 

 been so far completed that any errors 

 which may remain will not effect the 

 microscopical unit sought. With re- 

 gard to the exact subdivision of the lat- 

 ter unit, I can only report progress." 

 The author's theory regarding the 

 method which Nobert may possibly 

 have employed in the production of 

 his test-plate was briefly stated thus : 

 " When a diamond is ground to a knife 

 edge, this edge is still made of sep- 

 arate crystals, though we may not be 

 able to see them, and a perfect line is 

 obtained only when the ruling is done 

 by a single crystal. When a good 

 knife-edge has been obtained, the pre- 

 paration for ruling consists in finding 

 a good crystal." ..." When a dia- 

 mond has been so adjusted as to yield 

 lines of the best character,' its rul- 

 ing qualities improve with use. If 

 Nobert had any so-called secret, I be- 

 lieve this to have been its substance." 

 The problem of fine ruling consists 

 of two parts, — " first, in tracing of va- 

 rying degrees of fineness ; and second, 

 in making the interlinear spaces equal. 

 The latter part of the problem is 

 purely mechanical, and presents no 

 difficulties which cannot be overcome 

 by mechanical skill." The most 

 marked characteristics of lines of 



