British Association. 287 
was perfectly dark until the appearance of a celestial body, and then it 
became perfectly illuminated. 
The instrument is formed in the manner of a common spy-glass, with 
a break in the centre of the tube to admit light. Below is a spring, with 
a small ivory ball attached. The observer looks through one end of the 
instrument and sees that all is dulness; but when the spring is raised, 
the space becomes illuminated with light, showing that the introduction 
of the ball is necessary to render the light visible. 
Professor C. P1azz1 Smyru then entered into a history and explanation 
of the time-signals. 
“On a Printing-Telegraph.” By Professor D. E. Huenes.—This in- 
strument possesses special merits not only for land lines, but for long 
sub-marine lines, from the fact of its requiring but one wave to each 
letter, and the sensitiveness and simplicity of the electrical arrangements. 
The following rates of speed were obtained in different lengths of cables :— 
Atlantic cable, ... 20.000. 2500 miles, 4 words per minute. 
REMC, COs, nnxe'cadnst'smate 2000 5... 96 - 
PO Ye PIA «she's siose'e sien ote LOU OS 55, eu i 
1. gig NA acco alt 500 ,, 24 
Menmrark-do., 2eiscecscces.es 360 ,, 22 2 
Masmiania do., ....03..26.c85. 240°, * 30 2s 
On aerial lines the average speed of good operators is forty words per 
minute. 
Mr W. Coox read a paper on the Printing-Telegraph invented by 
M. le Chevallier Bonelli (the former Director of Telegraph in Italy), 
in which the messages are printed by means of types.—The telegraph 
transmitted a message in six seconds, and it was quite possible to work it 
at a long distance. 
Mr W. Lapp exhibited a new form of Syren, adapted for the lecture- 
table, to illustrate acoustics and harmony. ; 
Mr Lapp exhibited an acoustic telegraph for the transmission of 
musical notes and sounds between distant points, this ingenious con- 
trivance being the invention of a schoolmaster at Frankfort, whom Mr 
Ladd had met with in his travels. 
Mr Lapp also exhibited a small electromotive engine, constructed by 
himself on a new principle, and calculated to lift a weight of twenty-two 
lbs. eight inches per minute. . 
Professor CHEVALLIER introduced a new series of numbers, invented by 
Mr R. 8. Browne, for expressing the distances between the planets. 
Professor C. W. Siemens read a paper ‘‘ On the Electrical Resistance 
and the Electrification of India-rubber under a pressure of 300 tons,” 
detailing experiments he had made with the Malta and Alexandria sub- 
marine cable, &c.—The Professor explained that, as Mr Jenkin had pre- 
viously discovered that electrification is not influenced by temperature, 
so his own experiments went to show that it, was not affected by pressure ; 
but the latter exercised this abnormal influence on these materials, that it 
increased the resistance in gutta percha, but decreased it in India-rubber. 
‘* Report on Luminous Meteors.” By Mr J. Guaisuer. — 
‘“‘ Description of a Solar Kye-piece,” made by the Rey. Mr Dawes, 
F.R.A.S. By Dr Lez.—The peculiarity of the instrument consisted in 
having a metallic slide, with perforations of different sizes, which crossed 
the eye-tube at right angles, just at the focus of the object-glass, and 
