444 
POPULAR SCIENCE REVIEW. 
fork is placed against the tragus of his ear he hears the higher octave to the 
almost entire exclusion of the lower, and with a clearness that reminds him 
•of the sensation perceived when an Ut 4 resonator, placed to the ear, rein- 
forces its proper note. The higher octaves of several forks have been thus 
perceived, but the forks from Ut 3 to Ut 4 inclusive appear to give the best 
results. 
The Laws of Frictional Electricity . — M. L. Joulin has investigated the 
laws of frictional electricity with a machine suggested by the electrical 
phenomena often observed in belts used for transmitting power. A very 
great quantity of electricity is thus produced, capable of giving long brushes 
and sparks, of deviating a galvanometer needle, of decomposing water, and 
in Geissler tubes of showing the stratification of the light. A new 
method of measuring electric tension has been employed, dependent on the 
.greatest distance at which a brush is perceptible on a given sphere when 
brought near the electrified body. The experiment was varied by using 
pulleys of various metals or non-conductors, and by changing the velocity 
tension and temperature. In arranging the results there seem to be three 
causes influencing the production of electricity — the velocity of separa- 
tion of the parts of the belt and pulley, the complex mechanical action of 
bending the belt, and the temperature of the two materials. — “Ann. de 
Chim. et de Phys.” ii. p. 5. 
Experiments with Thermometers.— At the British Association Meeting 
^Belfast), Mr. G. J. Symons exhibited a series of fourteen very carefully made 
thermometers, all differing either in the size or shape of the bulbs, or in 
the material with which they were filled, some being mercurial and some 
containing alcohol. They had been specially constructed with a view to 
testing the relative sensitiveness of different patterns and sizes. The 
results of the experiments had been printed in the “ Quarterly Journal ” 
of the Meteorological Society, and were as follows : — (1) That very large 
spherical mercurial bulbs are very little better than those filled with 
alcohol, but that with small bulbs mercury is much more sensitive. The 
new minimum thermometers (the bifurcated and the double cylinders), 
-introduced respectively by Messrs. Casella and Hicks, were highly praised. 
Mr. Symons said that he brought them before the section mainly in 
order to offer the loan of the entire series to any experimentalist with 
more leisure than himself, and who would develop and complete the 
inquiry which he had begun. 
Collision of Stars. — Mr. G. J. Stoney, F.B.S., read a paper on' the results 
which would take place supposing two stars to come into collision, the 
effect being a great increase in light and heat. He pointed out that there 
might be many cold or dark stars in space of which science knows 
nothing. There are some stars which appear and disappear at intervals. 
This might be due to one star passing and “ wiping ” another. — “ British 
Association Reports.” 
A New Deep-Sea Thermometer. — Mr. Negretti exhibited (at the British 
Association, Belfast) a very clever invention in connection with thermo- 
meters for ascertaining deep-sea temperatures. A deep-sea minimum 
Thermometer will register the lowest temperature through which it passes, 
«o if a layer of water above the bottom of the ocean is colder than the 
