THE FIRE PISTON—-BALFOUR. 567 
known for some time in England, having been first mentioned nearly 
a year and a half previously by Mr. Fletcher at a meeting for philo- 
sophical experiments and conversations, which was then held weekly 
at Mr. Nicholson’s house. He adds, “It is a curious phenomenon, 
and deserves investigation.” No one at the time explained the cause 
of the phenomenon, which had been accidentally noticed and had not 
been arrived at by direct scientific experiment. Nicholson’s state- 
ment is interesting, not only as assigning the first observation of this 
physical effect to an earlier date (somewhere about the middle of the 
year 1801), but also as ascribing to an Englishman its discovery. 
In later days the experiment of igniting tinder in a compression 
pump became a common one in physical laboratories, and fire pistons 
were specially made for the purpose. These consist usually of 
cylinders of brass, closed at the lower end and very accurately bored 
or gauged. Into the bore fits a piston rod, carefully packed at the 
lower end, so as to occupy the bore as completely as possible. At 
the lower extremity of this piston rod is a cup-like depression, in 
which a piece of amadou can be placed. By driving the piston rod 
home very forcibly the column of air in the cylinder is violently 
compressed into a fraction of its normal length, the sudden conden- 
sation generating an amount of heat amply sufficient to ignite the 
tinder. The piston rod is at once withdrawn as quickly as possible 
and the tinder is found to be glowing, and a sulphured match may 
be lighted from it. In place of the brass cylinder and piston one of 
glass may be used, and the vapor of carbon bisulphide can be 
exploded by the compression, the flash being plainly visible through 
the glass. 
Not only was this principle adapted for scientific illustration, but 
it was also applied to domestic use. Who was the first person to 
adapt the air-compression method for use in everyday life may 
never be known. We know, however, that its potentialities for 
utilitarian purposes were recognized not very long after the scientific 
interest had been roused. Among the specifications of English 
patents for the year 1807 there is one, dated February 5, No. 3007, 
recording an invention by Richard Lorentz of “an instrument for 
producing instantaneous fire.” The figure of this instrument is re- 
produced here (fig. 1 on pl. 11), and specification runs as follows: 
The illustration shows the construction of my machine or instrument for 
producing instantaneous fire. @ represents the cap or head of a staff or stick, 
having therein a cavity or space for containing the prepared fungus known by 
the name of German tinder, or for containing common tinder of rags, or any 
other very combustible substance. ¢ is the outer end of the rod of a syringe, 
which works by a piston in the upper part of the staff, and by a stroke of about 
twelve inches forces the common air with great velocity and in an highly con- 
densed state through a small aperture against the combustible matter included 
41780—08——40 
