392 
[May, 
Notes . 
Physics. 
A galvanometer, which measures the strength of the eleCtric 
current direCtly, instead of indirectly, as in the instruments com- 
monly employed, has, we learn from the “ Engineering and 
Mining Journal,” been constructed by Prof. Dolbear, of Tufts 
College. He utilises the force exerted by a common helix to draw 
the core within itself when a current is passed through it, which 
is direCtly proportional to the strength of the current. A simple 
mechanism, consisting of a spiral spring, a graduated scale, and 
a pointer, suffices to measure the strength of the current. 
A simple contrivance for holding the objeCt beneath the stage 
of the microscope, when extreme obliquity of illumination is 
required, has been devised by Mr. John Phin, of New York, and 
has the advantage of being easily adapted to any microscope. 
The little sub-stage, with clips attached, is slid into the aperture 
in the stage. The mode of use will be obvious. Mr. Phin also 
states that the plan of holding the objeCt beneath the stage is 
not new, having been invented by Mr. C. A. Spencer about 
twenty years ago. 
Mr. E. J. Newton, of the Quekett Microscopical Club, has 
constructed an enlarged model of the brain of a cockroach 
( Blatta orientalis). The brain, properly hardened, was cut into 
sections of i-ioooth of an inch in thickness, and after the sec- 
tions were mounted a careful outline of each was made by the 
camera lucida, on a piece of soft pine-wood of suitable thickness. 
Each slice was carefully cut out with a fine saw, and the whole 
piled together to form the magnified model. The surface of each 
seCtion was carefully coloured, after the original preparations, to 
represent the appearance presented under the microscope. 
The “Journal of the Royal Microscopical Society” has com- 
pleted its first annual volume. The Fellows may be congratu- 
lated upon the improved form their official publication has taken. 
The volume contains 402 pages, comprising the whole of the 
papers read before the Society, seventeen plates besides w ood- 
cuts in the text, full reports of the meetings, translations of 
