ACCESSORY INSTRUMENTS. 



157 



by its opposite end to a burner, the tube will allow of its being 

 moved about to all parts of the table where it may be re- 

 quired. If the table be a fixture, a large gas pipe, having a 

 number of screws at the top to receive union joints, may be 

 brought up through its centre, and as many burners as may 

 be required attached to the central pipe by means of flexible 

 tubes. In all cases the argand burner should be mounted 

 on a stand similar to that of the oil lamps, figs. 105 and 107, so 

 that the flame may be raised or depressed to suit every kind 

 of microscope. 



In order to render the light from a Cambridge lamp as per- 

 fect when the oil has become low as when the reservoir is fuU, 



Mr. Spencer, of 

 Blackheath, has re- 

 commended to the 

 author the follow- 

 ing very excellent 

 contrivance. In 

 fig. 110 is shown 

 the burner, and a 

 section of the re- 

 servoir, of a Cam- 

 bridge lamp, the 

 latter having a dia- 

 phragm, D, firmly 

 fixed by solder to 

 the top and aU 

 sides of its inte- 

 rior, except the 

 lower edge, where it is distant from the bottom one-sixteenth 

 part of an inch. On the opposite side of the reservoir is 

 firmly screwed a stop-cock, S, with fiexible tube of gutta 

 percha or other material, and mouth-piece, T. When the 

 lamp burns dimly, from want of oil or short wick, remove the 

 cap. A, and breathe gently through the tube, T, till the oil 

 rises to the proper level, L, and immediately close the stop- 

 cock. The lamp will then burn as brightly as it did when the 

 reservoir was full. 



