SCIENTIFIC SUMMARY. 
231 
sort of cypher, which will give all the letters of the alphabet by the suppres- 
sion of certain portions of the fundamental form. “Now,” says the Abbe, 
“ suppose rows of these compound characters to be placed on a sheet of pre- 
pared paper of a metallic nature, the words of the telegram to be sent are 
written on them with isolating ink, leaving the other parts of the small 
1 stereotyped ’ blocks untouched. The consequence is that the current is 
intercepted at every point touched by the ink, and a letter is imprinted on 
the prepared paper at the other end of the line where the telegram is to be 
received.” 
The Magnetic Polarity of Rifles. — Mr. J. Spiller has lately made some very 
interesting observations respecting the magnetic power assumed by rifles. 
He finds that all the long Enfield barrels of the arms in the possession of 
the volunteers of his company exhibit magnetic polarity as the result of the 
violent and repeated concussions attending their discharge in a direction 
parallel to the magnetic meridian. The Royal Arsenal range runs nearly 
north and south, and the rifles, when in use, are always pointed either due 
north or a few degrees towards the west — in fact, nearly in the direction 
indicated by a compass needle — so that the repeated shocks brought about 
by the explosion of the powder may, Mr. Spiller thinks, be considered 
equivalent to so many hard blows from a hammer, which, as is well known, 
have a similar effect. Mr. Spiller goes on to say that the magnetic charac- 
ter appears to be permanent, which would not be the case if the gun-barrels 
Avere of the softest description of malleable iron, and the region of the breech 
is, in every instance, possessed of north polarity, since it strongly attracts 
the south pole of the compass needle. These effects should not be noticed 
at all, or only to an inferior degree, in arms ordinarily fired in directions 
east and west ; and I imagine that by reversing our usual practice, if it were 
possible, and firing towards the south, the indications of polarity would be 
changed. 
Electric Guns. — At a late meeting of the Society of Natural Sciences of 
Seine-et-Oise, M. He Brettes exhibited a rifle on the Fiobert system, and 
Avhich is fired by means of electricity. This new invention, with which the 
Emperor appears to be much pleased, has the folloAving characters : — Two 
small electric batteries are enclosed in the stock, their conducting wires 
arrive at the surface of the breech, and can be put in communication with 
the extremity of a platinum wire, which traverses the cartridge. A simple 
pressure of the finger upon the trigger closes the electric circuit ; the cur- 
rent passes ; the platinum wire becomes at once redhot, and inflames the 
powder which surrounds it. The cartridges prepared for the needle gun 
carry their own priming, and a shock might inflame them ; the cases are 
thus liable to explode, and deprive the troops of their ammunition. With 
the new system this danger is impossible. It can, as the expense is trifling, 
be easily applied to guns of the ancient model. This ingenious weapon does 
not, however, seem likely to come into general use. Though exhibited by 
M. He Brettes, it was invented by M. Trouve. — Tide French Correspondence 
of Chemical News. 
Elongation of Electric Conductors. — Mr. E. Edlund has noticed a very 
interesting phenomenon in connection with the passage of an electric cur- 
rent along a wire conductor. He has found that when a current is passing 
VOL. VI. — NO. XXIII. S 
