ACCESSOEY INSTEUMENTS. 



149 



CHAPTER IV. 



THE LAMP. 



The lamp generally used for microscopic piirposes is of the 

 kind called the Cambridge or University Reading Lamp, as 

 shown by fig. 105 ; it is made of various shapes and sizes, and 

 consists of a circular reservoir about four or five inches in 

 diameter, and one or two inches in depth, having the tube 

 which conveys the oil to the wick, inserted into one side of 

 the lower part of the reservoir ; the tubular part containing 

 the wick and supporting the gallery or chimney holder, termed 

 the burner, is a little higher than the top of the reservoir ; 



this last is mounted on a small 

 square stem, about eighteen inches 

 high, rising from a heavy metal 

 stand or base, and passing through 

 the middle of the reservoir, which 

 is made to slip up and down upon 

 the stem, and is fixed at any height 

 by means of a tightening screw; 

 the burner is an argand one, and 

 the diameter of the wick about 

 three-quarters of an inch ; at the 

 111 *^ I Til bottom of the burner is screwed a 



liH | l tiipiiII_L •'^**^® ^^^ ^°^ catching the super- 



IT!^ t Kir fluous oil. Upon the same square 



stem supporting the reservoir may 

 be adapted a hood or shade of a 

 conical figure ; this, like the reser- 

 voir, slides up and down the stem, 

 and may be fixed at any required 

 height ; it is generally made of 

 metal, and is of a dark colour on 

 the outside, and in the inside is painted white, to throw the 

 light upon the table. Some shades cut out of paper that is 

 green on the outside and white in the inside, and fitted upon 



Fig. 105. 



