682 
POPULAE SCIENCE EEVIEW. 
pieces of glass are placed between a source of light and the spectroscope. The 
Abb6 remarks that, when lightning is observed by the spectroscope, it is 
therefore important to note the degree of visibility of the bright lines it give.s, 
for the thickness and opacity of clouds can vary them greatly. 
Wheatstone's new Thermo-electHc Battery— 'Piofessov Wheatstone has re- 
cently constructed a powerful thermo-electric battery. The batteiy, the effects 
of which were shown by Professor Wheatstone to a select circle of friends, is 
composed of sixty elements. In making it, an interesting and important fact 
observed by Marcus was confirmed— namely, that the power of the battery 
is greatly increased by repeatedly re-melting the aUoy composing the bars. 
This is probably due to the gradual breaking down of crystalline structure 
by fusion. Connecting the terminals of this battery, excited as Marcus’s, a 
brilliant spark was obtained, and about half an inch of fine platinum wire 
when interposed was raised to incandescence and fused ; water was decom- 
posed, and a penny electro-plated with silver in a few seconds, whilst an 
electro-magnet was made to lift upwards of a hundredweight and a half. 
Bright sparks were obtained from the primary and secondary terminals of a 
Euhmkorff coil connected with the battery. In fact, all the effects obtained 
from a small voltaic combination were reproduced with ease by this thermo- 
electric battery, the electro-motive force of which was carefully measured and 
found nearly equal to two of Daniell’s ceUs. 
ZOOLOGY AND COMPARATIVE ANATOMY. 
The Muscular Mechanism of the Ostrich's Leg has been very fully given by 
the Rev. Samuel Haughton, in a memoir in the Dublin Quarterly Journal of 
Science for July. The writer describes minutely the muscles, and then- 
relations and attachments, and then he proceeds to discuss the question 
of the mechanical value of the several structures. He demonstrates, with 
all the accuracy of a natural philosopher calculating the power of a system of 
levers, the exact force which each muscular combination is capable of, and he 
frames some interesting analogies between the mechanism of an ostrich’s leg 
and that of a Cornish engine. Any observer who examines the gait of the 
Ostrich, Emu, or Rhea, cannot fail to be struck with the ungainly effect pro- 
duced in the appearance of the animal when walking slowly, by the abrupt 
and odd-looking lifting of the foot caused by the structure of the heel joint, 
giving an effect like that of “ string-halt ” in horses ; but this unpleasing 
impression would be rapidly converted into admiration if he could see the 
bird in rapid motion over rough ground, springing from foot to foot, and 
bending the foot as it left the ground with the rapidity of lightning, avoiding 
skilfully, without an apparent effort, the dangers of the rough soil. The 
force expended in propelling the body of the ostrich forward is ten times 
the force employed in restoring the legs of the animal preparatory to its 
next spring ; more exactly, as 335-5 to 33*75. This enormous force acts 
upon bony supports, which are required, by the necessities of the bird’s 
existence, to be as delicate and light as possible ; and it is, moreover, exerted 
