THE MICROSCOPE. 85 
use the instrument as a means of research and not as a play- 
thing. 
First and foremost, the simpler the working parts are, the 
better. Complication means a waste of time with no corre- 
sponding gain. When a microscope becomes a mass of 
machinery with screws, wheels, pinions and a thousand and 
one appliances, its sphere of usefulness is gone. 
The tube of the microscope should be short and, if the 
owner has money for objectives, a draw tube and an ampli- 
fier are utterly useless. ‘The use of a draw tube is to increase 
the length of the tube of the microscope and thus enlarge 
the image formed by the objective, but it must be at once 
evident that the increased size of the image is counterbal- 
anced by a corresponding loss in distinctness and_brilliancy. 
But few objectives are made which will stand the strain of 
the higher oculars and a drawtube. ‘The continental workers 
adopt the other method of using objectives of greater mag- 
nifying power to obtain the desired amplification and it is only 
necessary to refer to their published figures to show the 
great superiority of their method. ‘The writer would there- 
fore advise instruments with short tubes, the amplification of 
the image to depend on the objective. 
There should be two methods of regulating the distance 
between the objective and the object: one by which it can 
be rapidly increased or diminished, while the other works at 
a greatly lower rate of speed and thus is suitable for small 
distances. These are called respectively the coarse and fine 
adjustments. There have been many plans for regulating the 
coarse adjustment, but two, however, having any extensive 
