SCIENTIFIC SUMMARY. 
429 
colour, a waxy or vitreous lustre, and when in thin flakes is feebly trans- 
lucent. The hardness is 5*5, the specific gravity 3-28, and the analytical 
results point to the formula 3(CaO, FeO), 2Si0 2 ,Ba0 3 , as representing its 
composition. — Verh. Geolog. Vereins Stockhohns, iii. 229. 
Sphaei'ocoboltite. — Weisbach has given this name to a new member of the 
calcite group occurring at Kiechelsdorf associated with the beautiful mineral 
roselite. It is found in spheroidal masses, black on the exterior, but ex- 
hibiting on the interior the fine red colour of erythrite (cobalt arsenate 
hydrate). It possesses the specific gravity of 4-02 and the following com- 
position : — 
Cobalt oxide 64-25 
Carbonic acid 35-75 
100-00 
and is therefore a cobalt carbonate. — Jahrbuchfur Minercilogie, 1877, 409. 
PHYSICS. 
The Telephone . — During the recent session of the British Association at 
Plymouth, the lion’s share of attention was unquestionably given to the 
telephone. Wherever the instrument was to be exhibited — whether in the 
Physical or in the Mechanical sections, or at Mr. Preece’s popular evening 
lecture — there were always crowded audiences eager to learn something 
about so novel an apparatus. At the soirees , too, the telephone stood above 
everything else as the centre of attraction; and knots of people were crowded 
round the instrument, anxious to converse with friends in distant apart- 
ments. The interest in this subject culminated in the arrival of Professor 
Graham Bell, the inventor of the u talking telegraph.” 
Mr, Bell is a native of Edinburgh, who emigrated to the New World, 
and settled first in Montreal, and afterwards at Boston. Following his 
father’s profession as an elocutionist and teacher of the deaf and dumb, he 
had been led to study with great care the manner in which air is thrown 
into vibration by the vocal cords, and the way in which these vibrations 
are received by the organ of hearing. By experiments on a dead human 
ear, he conceived the possibility of throwing a membranous disc, or artifi- 
cial drum, into a state of vibration by the voice, and of transmitting these 
vibrations along an electric wire. His early experiments, made five years 
ago, were the very reverse of successful ; but by successive modifications he 
so improved the instrument that he was able to exhibit at the Centennial 
Exhibition last year a telephone worthy of Sir William Thomson’s notice. 
It was to this instrument that the Glasgow professor referred when ad- 
dressing the Physical section of the British Association at last year’s 
meeting. 
Since the close of the Philadelphia Exhibition, the development of the 
telephone has occupied Professor Bell’s constant attention. Every part of 
the apparatus has been modified again and again, and even the instrument 
which he exhibited at Plymouth will probably be superseded in due course 
by improved forms. But in its present state — immature as the inventor 
