46 



THE MICROSCOPE 



Electric 

 lamp. 



Fig. 38.— No. 3332, " Pointolite " Lamp 



class of illumination ; and the Beck electric lamp is a convenient 



form which takes either kind of electric bulb. 



The lamp has adjustment so that the beam of light can be 



placed at any height 

 between 3 and 9 inches 

 above the level of the 

 table. 



The stand (A) is in 

 the form of a heavy 

 ring with a section cut 

 ofi so that it can be 

 placed close to the 

 microscope. 



A vertical rod (B) is 

 fixed into this ring. On 

 this rod a bracket (C) 

 slides up and down 

 and can be clamped in 

 position at any point 

 by a milled head (E). 

 This bracket can also 



be inclined at any angle and clamped by another milled head (F). 



These clamps are independent of each other, and either can 



be used without disturbing the other adjustment. 



On the bracket (C) is fixed another vertical rod (G), which, by 



means of the arm (H), carries the electric light bulb. This can 



be moved up and down the vertical rod G and fixed by a 



clamp screw (J) in such a 



position that the incan- 

 descent point of the 



" Pointolite " or the most 



luminous portion of the 



filament of an electric 



bulb can be placed in the 



optic axis of the bull's-eye 



condenser (K). 



The arm (H) has at- 

 tached to it a thin metal 



cylindrical tube with a 



circular aperture which 



forms a shield to cut off 



stray light from the room, 



and when the electric bulb 



has been adjusted to the Fig. 39. — No. 3332, "Pointolite" Lamp. 



optic axis of the condenser, 



this tube can be moved up and down till the aperture in the 



metal casing is also opposite the condenser (K). 



The condenser (K) is carried in a mount which has two slides 



