32 The Microscope. 



1. They are tapering ; the variation in .5 inch length of 

 screw being .005 inch. 



2. They are not ronnd ; the difference between the largest 

 and smallest diameter in one tap being a little over .001 inch. 



3. They are unlike in diameter at their largest diameters, 

 one measuring .8 and .003 inch, while the other is exactly .8 inch. 



4. The threads do not correspond, which is evidence that 

 either the angles vary or that they are irregular. 



We look in vain through the " proceedings " for any report 

 of many interesting and valuable remarks made under the head 

 of "■ discussions." These " remarks " on the various papers read 

 were many times as valuable as the papers themselves, and it 

 was understood by many of us while at the meeting, that these 

 discussions would be reported, even in the absence of a stenog- 

 rapher. Two things, finally, we wish were different : first, 

 we miss accounts of these " discussions," as engaged in by Pres. 

 Cox, Dr. Detmers, Prof. Lattimore, Prof. Smith, and many oth- 

 ers; and second, we see no use in printing the matter found be- 

 tween pages 234 and 250. The volume appears in good paper, 

 clear type, and shows unusual care in its editorial work. As a 

 whole, then, we are glad to announce that the volume is above 

 the average, and, in our opinion, excels any ever issued by the 

 society. The Microscope thanks the " committee on publica- 

 tion," and especially the secretary, Prof Kellicott, for the com- 

 pletion of this task, which is to some extent a thankless one. 



NEW LENS HOLDER. 



BY R. H. WARD, M. D., F. R. M. S., TROY, N. Y. 



THE large, heavy doublets sold as " engravers' glasses " have 

 been used with great satisfaction in the preliminary exam- 

 ination of herbarium specimens or of handwriting ; in the selec- 

 tion from among large masses of material, as of fabrics or 

 mixed fibres, or other substances supposed to contain inequali- 

 ties or adulterations, the portions requiring further investiga- 

 tion ; and in performing under the lenses such manipulations or 

 dissections as require only a low amplification. For these pur- 

 poses the writer has been led to devise and employ a stand, 

 arranged somewhat like the stands used by engravers, which is 



