102 THE AMERICAN MONTHLY [March 



base, B, on which it stands vertically. It is sometimes fitted 

 with lens powers of 8, 12, and 16 diameters, the latter of which 

 is probably its limit for non-achromatic lenses. But, of course i 

 the design is suitable for any similar body, however high class. 

 It is quite free from vibration, and admits of the body being 

 raised or lowered, and also swivelled in any direction ; and the 

 Si^me remarks apply to the mirror or condenser fitted beneath 

 the stage. For those who could afterwards get a better instru- 

 ment, this one need not be discarded, for it will always be found 

 highly useful for viewing the general structure and beauty of 

 small insects, the parts of plants, and for a host of other pur- 

 poses. The smoker may test his tobacco for adulteration, and 

 the housewife her flour, oatmeal, etc., for mites. 



A few glass cells should be built for properly viewing live 

 insects. This may be done by cutting off short pieces of 3-16 in. 

 glass tube, and, after carefully rubbing the ends down flat and 

 parallel on sandstone with water, cementing them to slips of 

 glass with Canada balsam; a loose slip of glass being used to 

 confine the insect within the cell, where all its motions may be 

 watched. For objects not requiring the light through them, a 

 dead black slide should be used. In the outer corner of the 

 stage there is a J -in. hole, to which may be fastened a simple 

 swivel for a stage forceps. A small drawing-pen makes a very 

 fair substitute for a stage forceps. 



But to return to the "Student's Microscope." Cut off' the 

 mirror portion from the lens portion, and to the latter solder or 

 sweat neatly a brass armj^iece of the form shown, and having a 

 hole in the centre of end through which the screwed pin is 

 passed to clamp it in any position to the slotted upright of stand. 

 Th^ stand and upright may be made of brass or of wrought 

 iron, the stand (which is square) having a groove formed in its 

 upper surface into which the foot of upright is fitted and sol- 

 dered, or, better still, brazed, if the means are available. On to 

 the arm is fitted and soldered the stem, i, which is a bit of brass 

 tubing, and on stem, i, is fitted and soldered the stage, s, which 

 is of 1-16 in. brass and fitted with steel or spring brass clijis to 

 hold the slides. 



The mirror portion should now be dealt with. Drill a small 

 hole through the base ring, b, and rivet a short piece of thin 



