1892.] THE MICEOSCOPE. 221 



a local circumscribed area, the same studied with a 1-15 homo- 

 geneous oil immersion lens of 1.35 N. A. in detail, as well as 

 microphotographed for permanent record, the slide being the 

 largest that has come under my notice, although larger and bet- 

 ter slides have been made by others, yet on a dissimilar plan, 

 and of course of greater perfection, merit, artistic skill, and 

 scientific value. 



To note additional devotion to the study, I may relate that I 

 have printed w^ith pen and ink, in neat and legible italic letters, 

 the specific names of the 2,300 figures in my copy of WoUe's N. 

 A. Diatomace^e, contiguous to each species, which makes the 

 book doubly useful, as a glance at any plate dispenses with the 

 use of the numerical tables of species on the opposite pages. 



Finally, in treating of this science we must not overlook the 

 marvelous searching analysis of the diatomist, in the study and 

 preparation of material of low percentages, whose successful 

 manipulation aggregates, out of unpromising material, millions 

 of the beautiful frustules whose final function is to entrance the 

 eyes under the lenses of high or low power. — From the Ameri- 

 can Mofithly Microscopical Jourtial for November, 1893. 



AMERICAN CONTINENTAL STAND. 



By frank ZENTMAYER, 



PHILADELPHIA, PA. 



This stand has been designed to meet the wants of those 

 workers who prefer the compact Continental model and yet are 

 conscious of its inherent defects. It is substantially a combina- 

 tion of the upper half of our celebrated American stands with the 

 lower half of the best Continental stands, and is adapted to have 

 added all the usual optical accessories of either class of mi- 

 croscopes. As offered, it answ^ers fully every want of the class- 

 room or laboratory at very moderate cost. 



The stand is constructed entirely of brass, handsomely finished 

 and polished. The base is of horseshoe form, filled with lead 

 for extra weight, and gives perfect steadiness in every position. A 

 stout pillar firmly supports the arm of the instrument on a trun- 

 nion-joint, which allows all inclinations from the perpendicular 

 to the horizontal position. The coarse and fine adjustments are 

 of the same style and construction as the famous Centennial stand. 

 The arm carrying the body is provided with two slides, the upper 

 and longer one bearing the tube with rack and pinion movement, 

 and sliding in the low^er one, which is controlled by a lever of the 

 second order, operated by a milled-headed micrometer screw in 

 convenient position at the back of the instrument. At the bottom 

 of the lower slide there is a shoulder against which the lever acts. 



