ARTIFICIAL LIGHT. 



other form of this lamp has the movement placed in the 

 case flatwise, thus allowing- the flame to burn within 

 three or four inches of the table. The lamp is thus ren- 

 dered very handy for use when direct light is wanted. 



The author has found, as a result of thousands of ex- 

 periments, that the very best artificial light for the pur- 

 pose of the microscopist is only to be had from a small 

 but very intense flame. The smaller the flame the better, 

 owing to the fact that there is less light diffused. We 

 therefore use and strongly recommend the smallest ker- 

 osene hand-lamp procurable, and fitted with a well-be- 

 haved burner of the smallest capacity. If possible let 

 the lamp bowl be so low that the flame will be, say three 

 or four inehes only above the table, thus adapting the 

 lamp for use by direct light. On other occasions the 

 lamp can be supported in a more elevated position. 

 With a little lamp of this description, in proper order y 

 all the most difficult tests known to the microscopist 

 can be well displayed, provided^ obviously, that the ob- 

 jective, etc., shall be competent for the work. It is of 

 importance, when any lamp provided with a chimney is 

 to be used, that the latter be kept scrupulously clean, 

 especially from a whitish film that forms on the interior. 

 A chimney may appear to be perfectly clean while cold, 

 but when heated the aforesaid film can be detected, and 

 should be removed, if delicate observations are in hand, 

 in which case it will be well, too, if the wick be three 

 or four weeks old, to remove the same and substitute a 

 fresh one. Even in the case of the small pattern of 

 lamp recommended there will be no occasion to force 



