446 



SUMMARY OF CUKRENT RESEARCHES RELATING TO 



in fig. 76 and subordinates figs. 1-4. The base is the lid of an ordi- 

 nary tin can about -i in. in diameter, into which molten lead has been 

 poured. Through the base passes a ^-in. bolt 7^ in. long, and forms 

 the core of the pillar. The limb S (fig. 1) is made out of a rectangular 

 brass or zinc plate, hollowed out for the brass-tube sleeve V, to which it 

 is soldered. Fig. 2 shows the stage as cut out of a rectangular brass 

 plate 4 in. by 4^ in. by f^^ in. Fig. 3 shows the mirror-fitting, T being 

 a bit of slotted brass tubing to fit tightly over the pillar at X. The 

 mode of putting all these parts together is shown in fig. 4, the whole 

 being kept rigidly in position by help of a nut L at top and at bottom 

 (not shown) of the core. The sleeve V is lined with cloth or felt for 



Fig. 76. 



coarse adjustment of the tube. Objective and ocular should be bought 

 from an optician. The ingenious fine-adjustment is illustrated in 

 figs. 1 and 4. Two pieces of ^j-in. sheet-brass, 3 in. long and if in. 

 wide, are cut and bent so as to grip tightly the sides of the stage (E, F, 

 fig. 2). On one of the pieces near each end two brass points ^ in. high 

 must be soldered (n and o, E, fig. 2). To the other piece, F, solder a 

 nut, C. This nut should be fitted with a thumbscrew 1^ in. long (25 to 

 50 threads per in.), the tip of which should be conical. In a rectangular 

 brass plate 4^ in. by 3 in. and ^ in. thick bore a i-in. hole at the centre. 

 Shallow depressions must be punched in the plate to correspond with 

 the points n and o and the screw H (fig. 4). A spring clip J (fig. 1) 

 holds the plate K in close contact with the three points. A graduated 

 drum attached to the screwhead and a pointer fastened, as shown at M 

 (fig. 1), afl'ord a means for estimating the amount of vertical move- 

 ment of the plate. In figs. 1 and 4 the stage is shown as assembled. 

 In a fine-adjustment of this design a certain amount of lateral move- 

 ment of the image is unavoidable. However, this is partly compensated 

 by the fact tliat there is absolutely no lost motion. 



Grundlach Microscope, Model A H 09.* — This Microscope is 

 primarily intended for school and college use. The coarse-adjustment 



* Catalogue, Gundlach-Manhattan Optical Co., Rochester, New York. 



