WITH THE MICROSCOPE. 43 



marked on the slide itself, and the same spot can always be found 

 by looking for these numbers on the finder, moving the stage till they 

 come in the centre, and then substituting the slide for the finder. 

 The numbers and lines are photographed on the finder which is 

 made by Messrs. Smith and Beck, and costs "js. 6d. A few of the 

 squares of a Maltwood's finder are represented in pi. XIII, fig. 65. 



68. Mr. Briclgiuan's Finder which is sold by Mr. Baker, of Hoi- 

 born, consists of a curved bar fixed to the stand of the microscope 

 and capable of being moved upwards and downwards upon a hinge 

 joint. The bar terminates with a fine point, and when pressed down, 

 this point comes upon a piece of paper gummed to one end of the 

 slide and makes a slight prick, or it may be tipped with ink if pre- 

 ferred. When the observer sees an object which he desires to find 

 again, a mark is made with the point. In order to find this same 

 spot at any future time, it is of course only necessary to place the 

 slide in such a position that the original mark exactly corresponds 

 with the point of the finder, and the part of the specimen must then 

 be again in the centre of the field. The plan is so simple and effica- 

 cious, that it will, I think, completely supersede the various finders 

 now in use. 



INSTRUMENTS AND APPARATUS REQUIRED IN GENERAL MICRO- 

 SCOPICAL RESEARCH. 



69. Spirit Lamp. The spirit lamp may be made of brass, tin, or 

 glass fitted with a ground glass cap. It may be fitted with a stand 

 for holding watch-glasses, pi. XIV, fig. 70. Brass lamps, to which 

 a small retort-stand is fitted, may also be purchased of the instru- 

 ment makers. 



70. Wire Retort Stands. Simple wire stands, made like retort- 

 stands, which are fixed to a heavy leaden foot, will be found exceed- 

 ingly useful little instruments to the microscopical observer. The 

 rings can be readily raised or lowered at pleasure, and are well 

 adapted to support light objects, such as glass slides over a lamp, 

 test-tubes, flasks, and watch-glasses, pi. XIV, fig. 69. 



li. Tripods are made of thick iron wire, and are useful for sup- 

 porting several pieces of apparatus used in microscopical research, 

 pi. XIV, figs. 71, 72. 



72. Brass Plate. The brass plate should be about six inches long 

 by two broad, and about the thickness of thin millboard. It should 

 be supported on three legs, of a convenient height for the spirit or 

 other lamp to be placed underneath, or the brass plate may be sup- 

 ported on one of the rings adapted to Mr. Highley's lamp. It is used 



