OF THE MICROSCOPE. 27 



bles. Of the simple microscopes in use there are but two that re- 

 quire attention Raspail's and the Excelsior. For a description 

 of the elaborate dissecting microscopes of the London micro- 

 scope makers, as well as those of Nachet, and others, we must 

 refer to the large works of Carpenter, Beale, Frey, etc. 



Raspail's 3Iicroscope. In this instrument the magni- 

 fying glasses are supported by an arm which projects horizon- 

 tally from an upright column that screws into the top of a box, 

 in which the entire instrument is packed when it is not in use. 

 This column also supports a stage which may be moved up and 

 down by rack work, and a mirror for reflecting the light up- 

 wards through the object. This was the instrument so largely 

 used by Kaspail in his investigations into the structure of plants, 

 and described by him in his works, and hence it has been called 

 by his name. It resembles very closely the instrument called 

 the Society of Arts Simple Microscope, which is manufactured 

 by Mr. Field of Birmingham. 



The Excelsior Microscope. The accompanying en- 

 graving gives a very clear view of this microscope, which is 

 constructed as follows: 



To one end of the lid of a small wooden case or box, is at- 

 tached one of the ends of the box; and when the lid is reversed 

 and turned upside down, it may be slid into the groove which 

 usually receives it, and then forms a stand for the lenses and 

 glass stage, as is shown in engraving. The lenses and stage are 

 supported by a steel rod, D, the lower end of which is hinged 

 to the lid, so that it may be turned down and lie in a groove 

 provided for it. When raised into the position shown in the 

 figure, it is held very securely in place by means of the button, 

 E; and this button also serves to retain it in the groove when 

 it is turned down. The glass stage, G, which is fitted into a 

 frame of hard rubber, slides easily on the stem, D, so as to be 

 readily adjustable for focus, while at the same time it may be 

 firmly fixed, by means of a set-screw, at any desired height, 

 and will then serve as a stage for dissecting purposes. The 

 frame which holds the lenses fits on to the top of the stem. A 

 mirror, H, is fitted into the case, and is readily adjustable by 

 means of the button shown on the outside, so that light may 



