6 
the geese in England could supply of quills in a year, a matter of 
no inconsiderable importance in these days of universal education. 
In connection with the subject of gun-making is that of ex- 
plosives for guns. It has been proved that those explosives 
which furnish the largest proportion of gaseous products, and 
whose explosion is attended by the smallest amount of heat, exerts 
the least erosive action on the inner surface of the gun. To com- 
bine these desiderata with the property of a smokeless powder 
has been for some years the aim of many practical chemists, but 
although many kinds have been invented and tried with partial 
success, such as the nitro-cellulose powder of Colonel Schultze, 
and the nitro-glycerine powder of Mr. Nobel, none is entirely 
satisfactory, the almost insurmountable difficulty being to produce 
a powder which shall remain free from chemical changes when 
exposed to extreme variations of temperature. Some months ago 
an experiment was made in London with the Giffard gun, in 
which liquified carbonic acid gas is used as the expulsive agent. 
The liquid is contained in a small steel magazine attached to the 
under-side of the gun, and is sufficient to discharge three hundred 
shots. The charge of liquid for each round is contained in a 
special chamber, and is released by the pulling of the trigger. 
The bullet is dropped separately into an orifice in the breech 
block. The pressure of the fluid in the magazine is five hundred 
pounds to the square inch. There is no heating of the barrel by 
this new propelling force, nor is there any erosion of the inner 
surface of the gun, and merely a slight vapour, which instantly 
fades away, is noticeable when the gun is discharged. 
Although considerably behind either France or America in the 
use of the telephone, we are rapidly increasing our means of 
telephonic communication with our friends in the United King- 
dom, and it is hoped that before many weeks have elapsed the 
telephonic cable between London and Paris will be completed. 
The line will be laid via Maidstone, Ashford, Folkestone, Dover, 
and St. Margaret’s Bay to Calais. Messrs. Siemens are the 
electrical engineers to the line, which is the first real submarine 
telephonic cable in existence. The number of telephones now in 
use in this country is ninety-nine thousand, and in Ameriea they 
have reached the immense number of over two hundred and 
twenty thousand. Only thirteen years have elapsed since the 
telephone was first employed as a practical apparatus, and there 
are now upwards of one million telephones in working order 
throughout the world. 
A new species of mechanical telephone has lately been invented 
by Mr. Mellett, of Massachusetts, in which electrical agency is 
altogether discarded. This instrument, which is called the ‘ Pul- 
