STUDENTS’ MICROSCOPES. 325 
MAGNIFYING POWERS. 
Quality more than quantity. 
Theoretical. — One inch X 10. Oculars and objectives as above, X 50, 
, 200, 400, 800. 
Practical. — Should approximate to this. 
ACCESSORIES 
Essential, and should be PEE free. 
ie glass slides and covers; stage-plates with ledge ; pipettes ; pliers ; and 
needles mounted in handles 
Desirable, for medical and general use. 
Compressorium, or animalcule cage. 
0 
Graduated Draw-tube. 
Cylindrical tad below stage, to use ocular for achromatic condenser. 
Reagents. (In twelve one or two ounce via 
Turn table, ey mounting materials. 
Desirable, more for general than medical use. 
Condensing lens, on separate stand, for opaque objects, and for parallel 
light, ete. ; ; Or condensing lens to limb or stage of instrument, for opaque 
objects; or mirror on curved arm, to swing above stage, for opaque ob- 
jects; or mirror removable to sta age or se parate stand for opaque sein 
Spotted lens, or glass paraboloid, for translucent objects. 
Stage forceps. 
Maltwood finder. 
PR 
Including walnut or mahogany ae ye to $100. Varies with quantity 
and quality of work and reputation of maker. 
Less, at present, unsatisfactory. 
More, unnecessar 
ut double, by substituting binocular stand. 
. 
Occasional measurements the camera is entirely satisfactory. Where large numbers 
e to be made, this method is not sufficiently rapid and ie Dr. 
icrometer, a semicircle of ti ag Loos , graduated at the straight edge, and lying upon 
ii phragm in focus of the eye lens, is most used by the writer for this purpose, With low 
Ts the object is easily brought up obliquely to the foqoiren position; oe high powers the 
Jackson adjusting screw The simplest 
oetlar micrometer, and best for EOI students’ use, ie a —_— — cut, to fit, from yai 
Patty o-hundredths of a 
and lying, only when used 1 a Dr, White's ary 
mg 7 Pe the diaphragm P the ocular 
tei anes thick circle is more durable, more easily obtained and handled, and capable of 
expectedly results, It should cost $2 or $3. 
