SCIENTIFIC SUMMARY. 
105 
News/’ December 6, 1872. We may mention that the first part of this 
paper treats cf the infiuence of polarisation on the phenomenon ; the second, 
that of the nature of the plate as regards absorption. 
A New Econoinic Galvanic Pile . — This, which is the invention of M. 
Gaiffe, is described in “Silliman’s Journal of Science,” November. He 
says, the high price of galvanic piles and the difficulty of procuring them, 
being often an obstacle to the applications wffiich might be made of them, I 
essayed the possibility of devising an apparatus that one could make any- 
where without the aid of the professional workman, with substantives of 
little value, widely spread in commerce, and possessing the essential quality 
of constancy in the effects. The pair which, after some trials, I have 
adopted, resembles Callaud’s in its form, used some years since on tele- 
graphic lines ; but its elements are different. It consists of a vessel into 
which dip two rods — one of lead the other of zinc. The leaden one 
descends to the bottom ; the zinc is one-half shorter. The bottom of the 
vessel is coated wdth red oxide of lead (minium), and the exciting liquid is 
water containing 10 per cent, of chlorhydrate of ammonia. The electro- 
motive force of this pile is about one-third of that of a Bunsen’s pair j its 
internal resistance is slight, and varies little j the chloride of zinc formed 
does not sensibly alter the conductivity of the exciting liquid ; its con- 
stancy is great ; finally, the expense is almost nothing when the circuit is 
open.” 
A N etu Pocket Spectroscope^ for which many advantages are claimed, is 
stated to have been invented by M. Hoffmann. It seems to be a very con- 
venient form of spectroscope, that can be carried in the waistcoat pocket, 
and is yet capable of really wonderful effects, considering its diminutive 
size, producing a large and brilliant spectrum, the violet rays of which 
extend far beyond the line G. It has a lens of rock crystal, with perfectly 
flat parallel faces at each end to keep out all particles of dust, &c. The 
organ of dispersion and analysis is a compound prismoid formed of three 
alternating prisms, one, of the most powerfiil dispersive flint glass that can 
be procured, between two reversed prisms of crown, the angles being 
specially and skilfully arranged. The combination is completed by an 
ordinary compound doublet lens, of suitable focal length. 
A House P'ire caused hy Electrical Apparatus. — It is stated that a fire 
recently broke out in the flooring of one of the offices of the W estern Union 
Telegraph Company in New York, which was found to have originated in 
a cable of cotton covered wire saturated with paraffin, through which the 
lines entered the office beneath the floor. From some cause, probably 
lightning, a connection had been formed between two through wires attached 
to large main batteries at the general office, and which were connected 
with opposite poles to the ground. Two large batteries were thus con- 
nected and thrown into short circuit, developing an intense heat and setting 
fire to the inflammable paraffin covering of the wire. If this singular 
occurrence had happened after the closing of the office at night, it might 
have resulted in the destruction of the building, and the cause of the fire 
would have remained a mystery. Of course an accident of this kind could 
hardly have been foreseen, but it serves to point out the necessity of caution 
in running wires under the peculiar conditions described. 
