FINDERS AND INDICATORS. 187 



is also otherwise useful to the microscopist. It consists 

 of a stage a, supported by a tube and socket, sliding on 

 an upright rod rising from the stand. This carries an 

 argand burner B ; a metal cone c rises to the level of the 

 burner, and is about one-eighth of an inch from its outer 

 margin. 



This arrangement gives a bright cylindrical flame. The 

 bottom of the stage a is covered with wire-gauze, to cut 

 off irregular currents of air, and thus secures a steady 

 fiame. Over the burner is placed a Lebloud's blue glass 

 chimney d. This corrects the colour of the flame to a 

 certain extent ; but it is still further rectified by a disc of 

 bluish-black neutral-tint glass e, fitted in a tube F, attached 

 obliquely to the shield G. G is a half- cylinder of metal, 

 which serves to shield the eyes from all extraneous light, 

 but may be rotated on the stage a by aid of the ivory 

 knot H, when the full light from the flame is desired. A 

 metallic reflector i, fixed on its supports^ so as to be 

 parallel to e, concentrates the light. By the combination 

 of the two glasses d and e, the yellow rays of the flame 

 are absorbed, and the arrangement affords a soft white 

 light, which may be still further improved by receiving 

 the rays on a concave mirror, backed with plaster-of- Paris 

 l; and where a very strong light is required, a condensing 

 lens should be interposed, as shown in the cut, between 

 the lamp and the mirror of the microscope. By removing 

 the shield G, and bringing the shade M over the burner, it 

 may be used as a reading-lamp. A retort ring n supports 

 a water-bath o, or a wrought- iron plate p, 6 inches by 2 J 

 inches, both used in mounting objects. The stop-cock q 

 gives the means of regulating the flame. The screw R 

 clamps the lamp-head at any height desired. The lamp 

 may be attached to any gas-supply by vulcanised India- 

 rubber tubing. 



Finders and Indicators. — A finder, as applied to the 

 microscope, is the means of registering the position of any 

 particular object in a slide : as, for instance, some particu- 

 larly good specimen of a diatom, so that it may be referred 

 to at a future time. The subject has been fully discussed 

 in the pages of the Quarterly Journal of Microscopical 

 Science. The traversing stage admits of such finders as 



