44: BEALE, ON THE MICROSCOPE. 
belief that many who possess microscopes are deterred from attempting any 
branch of original investigation solely by the great difficulty they experience 
in surmounting elementary detail and mere mechanical operations,—are my 
chief reasons for publishing this elementary course of lectures, which was 
delivered during the past winter.” 
We are sure many young workers, and many old ones too, 
will be glad to receive directions at Dr. Beale’s hands. The 
first lecture is devoted to that very important subject, the 
purchase of a microscope; and in future we shall refer our 
numerous correspondents on this point to Dr. Beale’s work. 
We might profitably insert the whole of this lecture, but as 
a specimen we give the author’s remarks on “ Students’ 
Microscopes :” 
“Mr. Salmon, Mr. Highley, and Mr. Matthews were, so far as I know, 
the first makers in London who brought out a really good, cheap, practical 
instrument, furmshed with foreign object-glasses. Mr. Highley’s pattern is 
now made by Mr. Ladd. 
“T would strongly recommend all who are about to purchase a student’s 
microscope to examine the instruments of these makers. I can also strongly 
recommend the educational microscope of Messrs. Smith and Beck, which, 
however, is somewhat more expensive, costing ten guineas with case. 
“The microscope made by Mr. Field, of Birmingham, which gained the 
medal at the Society of Arts, is, for the price, an exceedingly good instru- 
ment. It is provided with two eye-pieces, two object-glasses (magnifying 
from 25 to 200 diameters), bull’s-eye condenser forceps and a live box, and 
packed in mahogany case with this apparatus complete, costs only three 
guineas. 
“Those who wish for a microscope as perfect as it can be made in the 
present day I should advise to look at the beautiful instruments of Powell 
and Lealand, Ross, and Smith and Beck. I would also recommend those 
of Mr. Pillischer to attention. In alluding specially to these instruments I 
wish it to be distinctly understood that I do not in any way disparage the 
work of other and less celebrated makers, but having had some experience 
with those instruments to which I have directed your attention I feel it 
right to express an opinion upon them. 
“Tn chosing a microscope the following requirements should be borne in 
mind :— With reference to the optical part, the zzch object-glass should mag- 
nify not less than 30 diameters, and the quarter not less than 200, when the 
shallow eye-piece is applied. The field should be well lighted, and the lines 
of delicate objects submitted to examination should be sharp and well de- 
fined. The mirror should be large (at least two inches in Niamtetaed one 
side plane, the other concave, and it should be adapted to the body of the 
microscope in such a manner that very oblique rays of light may be made to 
impinge upon the object. 
** With regard to the mechanical portion of the microscope, the adjust- 
ments should work smoothly, and an object placed in the field for examina- 
tion should not appear to move or to vibrate when the screws are turned. 
The body should be provided with a joint, so that it may be inclined or 
Hices quite horizontally. The stage should be at least three inches in 
ength, by two and a half in width, and there should be a distance of at 
least an inch and a half from the centre of the opening in the stage over 
which the slide is placed, to the upright body. The motion of the slide upon 
