328 
POPULAR SCIENCE REVIEW. 
PHYSICS. 
A Spectroscope for the Invisible Rays at the Red End of the Spectrum . — 
The Council of the Royal Society recently voted some funds to Mr. C. 
Brooke, F.R.S., for the construction of a spectroscope to search for lines in 
the invisible rays beyond the red end of the spectrum. The instrument is 
now in course of construction by Mr. Browning, F.R.A.S., and the prisms, 
which are made of rock-salt, have already been ground, polished, and tested. 
As glass stops many of the ultra-red rays, it is necessary to use lenses and 
prisms of rock-salt. When the apparatus is finished, a spectrum will be 
projected on a screen, and then search will be made for the lines by means 
of a delicate thermo-electrometer, with a thermo-pile having a fine slit in 
front. “ It is found that the lines in the visible part of the spectrum con- 
tain no heat, so it is supposed that no rays of any kind fall at those points.” 
Physical Science at Cambridge. — After a series of long discussions and a 
considerable degree of opposition the new chair of Physical Science is about 
to be established at Cambridge. The Syndicate appointed for the purpose 
had to give up the notion of raising the funds by subscription from the 
several colleges. They confined their attention, therefore, to the means of 
raising sufficient funds only for carrying out the recommendations of the 
Physical Science Syndicate in their report dated Feb. 27, 1869. These 
were to provide the stipends of a Professor of Experimental Physics, of a 
demonstrator, and an attendant, requiring altogether a sum of 660/. per 
annum ; also to provide a capital sum of 5,000/. for a new building, and 
1,300/. for apparatus. The Syndicate are of opinion that these sums may 
be raised from the ordinary sources of revenue of the University, and that a 
small addition (viz. 2s. a head) to the amount of the annual capitation tax 
will suffice for the purpose. 
Fall of a Large Meteorite. — At the meeting of the Geological Society on 
March 23, Mr. R. II. Scott, F.G.S., communicated an extract from a letter 
addressed to him by M. Coumbary, Director of the Imperial Observatory of 
Constantinople, containing an account received from M. L. Carabello of the 
reported fall of a large meteorite near Mourzouk, in the district of Fezzan, 
in lat. 26° N. and long. 12° E. of Paris. It fell on the evening of the 25th 
December last, in the form of a great globe of fire, measuring nearly a 
m&tre in diameter ; on touching the earth it threw off strong sparks with a 
noise like the report of a pistol, and exhaled a peculiar odour. It fell near 
a group of Arabs, who were so much frightened by it that they “ immedi- 
ately discharged their guns at this incomprehensible monster.” 
Meteorological Observations in the Captive Balloon. — The yearly Report of 
the Aeronautical Society contains an account by Mr. Glaisher, F.R.S., of the 
results obtained by him in his observations of the thermometer and baro- 
meter in the Captive Balloon. He says that the Captive Balloon supplied, 
in a most admirable manner, the power of repetition of observations within 
1,000 ft., which no free balloon could do. Our knowledge of the humidity 
of the air, and of its temperature up to this elevation is very limited. Every 
ascent in the free balloon had proved that the theory of the decline of 1° of 
temperature in every increase of elevation was erroneous. In some ascents 
a decrease of more than 1° was met with in the first 100 ft., notwithstand- 
