436 
POPULAR SCIENCE REVIEW. 
of tlie water will drive the mercury from one chamber to the other. The 
depth of the ocean bottom will be indicated by the quantity of mercury so 
exchanged. The register of depth is very exact. This sounding instrument 
requires no line, and is, we believe, the first of the kind ever invented. 
How to Ascertain the Strength of Metals. — Various plans for this purpose 
have been used from time to time. That of Prof. Thurston is thus described : 
^‘Work has now been commenced upon the metals, and the Professor 
desires to obtain samples of all well-known brands ; the specimens to 
be 3| inches long, and of 1 inch round bar or f and ^ square bar, with, in 
each case, statements as concise as possible of the ores used and method 
of manufacture of the sample, with the understanding that the results 
may be published. The specimens may be sent to the Institute at any 
time. The work was interrupted May 24, and during the absence of Prof. 
Thurston to attend to his duties as a member of the United States 
Scientific Commission to Vienna, but have been resumed on his return in 
September. We noticed a specimen of Ulster iron taken from open 
market, which had twisted to the limit of the machine, over 200°, with- 
out breaking off. The specimens are turned down in the middle, the neck 
being 1 inch long and | inch in diameter, by Whitworth gauges.” 
MEDICAL SCIENCE. 
Spontaneous Coagulation of Milk is Caused hy Microzymas. — According to 
a paper by M. A. B^champ in a late number of the Journal de Pharmacie,” 
the main cause of the spontaneous coagulation of milk is the presence therein 
of minute living organisms, which may be detected in the milk by first 
diluting it with from five to six times its bulk of creosote water (neither 
the degree of concentration nor the mode of preparation of this fluid are 
quoted), and next filtering the milk, care being taken to protect the filter 
from dust. The filter is first washed with ether, for the purpose of elimi- 
nating the butter j next, with a dilute solution of carbonate of soda, for the 
purpose of dissolving some caseine ; and lastly with distilled water. On 
inspection with the microscope (magnifying power 600 diameters) the 
microzymas will be seen. 
Is there such a thing as Muscular Sensation f — The results of M. Bem- 
Eardt’s experiments to determine whether the so-called muscular sense” 
comes from the muscles or from some other source are not without some 
interest. The author does not deny a “ sense of force,” but claims that it 
may be only a consciousness of the degree of excitement in the nervous 
centre which acts on the muscle, or that it may be owing in part to sensa- 
tions in the soft parts adjacent to the muscle. Bernhardt passes in review 
the various arguments pro and con. Spiess and Schiff pronounce decidedly 
against sensation in the muscles. Mechanical and chemical excitements of 
the muscles produce neither pain nor reflex movements, as has been shown 
by Pikford and Arnold. Cramps, indeed, cause pain ; but this may result 
from compression of nervous filaments traversing the muscles. It is doubt- 
ful, moreover, whether the muscles receive sensory nerves ; for it has been 
