26 



THE AMERICAN MONTHLY 



[February, 



face from which the young foot-stalk 

 was at that stage not sufficiently elas- 

 tic to lift it, "while the zooid was com- 

 pelled by some innate influence to con- 

 tinue the secretion of the lorica, so 

 that one side took the shape of its ir- 

 regular support. 

 Trenton, N. J. 



o 



Swift's Fine- Adjustment. 



A form of fine-adjustment was in- 

 troduced by Mr. Swift, of London, 

 some time ago, which we vxnderstand 

 is not expensive to make, while it is 

 certainly very effective and smooth in 

 action. If the reader will turn to fig. 

 45, on page 239 of the preceding vol- 

 ume of this Journal, a cut of a stand 

 with this adjustment will be found. 

 It will be seen that the milled head 

 for fine focussing is placed on the side 

 of the limb, a position which is in 

 some respects advantageous. 



The mechanism of the slow motion 

 is shown in fig. 8. By turning the 



Fig. 8. — Swift's Fine-Adjustment. 



milled head the wedge-shaped piece 

 is moved laterally, and thus imparts 

 an up or down motion to the parts 

 bearing on the two rollers. 



The same adjustment is applied to 



the stand figured in fig. 9, which is 

 also made by Messrs. Swift & Son, 



Fig. 9. — Swift's Microscope. 



embodying certain features recom- 

 mended by Mr. E. M. Nelson. 



In this stand the stage is cut away 

 in front, so as to afford a view of the 

 substage apparatus, and thus facilitate 

 the use of accessories beneath the 

 stage. 



The stand is a very simple and good 

 one. It has a centering substage, with 

 a rack, and diaphragms are attached 

 so as to be readily swung aside and 

 removed from the carrier. The body- 

 tube divides, to make the stand more 

 portable. We have seen this stand 

 used with high-power objectives, for 

 w^hich it is perfectly well adapted. 

 o 



Measiiriug Blood-Corpuscles. 



In the December number of this 

 journal was printed an excellent arti- 

 cle by that careful and skilful observer, 



