This apparatus was devised by Dr. Adair Crawford (1748—1795) for his experiments
on animal heat. Respired air was compared with pure air by putting samples
in the brass cylinders under certain controlled conditions. The whole was then put
in a hot water bath for ten minutes, and then quickly transferred to the prepared
tinned vessels in which the contained water was warmed by the cylinders. Long,
narrow thermometers reading to tenths of a degree were used to note the rise after
various periods of time, usually up to twelve minutes (sec Cat. 200 for such thermometers).
Differences of temperature were about two-tenths of a degree. Of the
cylinders, Crawford writes (1788, p. 187):
In constructing the above described apparatus, which was made by Messrs Nairne
and Blunt, great care was taken that the brass cylinders should be precisely equal
in weight, dimensions, and capacity. Their weight is 7 ounces, 3 drams, 38 grains
troy each; the length is 8 inches and 7/s; the breadth 2 inches 3/s near to their
upper extremity, and 2 inches 5/8 near to the bottom. They are each of them
capable of containing twenty ounces Troy of water, and consequently the solid
content is 37.91 cubic inches. The tinned vessels are also equal to each other in
weight and dimensions. They are covered with thick flannel for the purpose of
confining, as much as possible, the heat imparted to the water by the cylinders.
The bulbs of the thermometers were not more than 2/10 of an inch in diameter,
in consequence of which they were very sensible; and their bores were so minute
as to admit of a large scale, each degree of Farhenheit (Inc] being divided into ten
equal parts, distinctly visible to the naked eye.
Van Marum wrote to Nairne & Blunt asking for an apparatus like that of Mr.
Crawford, and it was supplied by them in 1792. The bill is dated 24 August, 1792,
and reads: “A Dr. Crawford’s instrument for heat with two thermometers as Dr.
Crawford’s. The inside of the vessels gilt £ 24-3-0. 3 small and 1 large packing cases 9s
6d” . Subsequent, related, items were: “ 5 December. 2 ivory scale thermometers divided
into tenths £ 5-5-0. A metal scale thermometer with 2 scales in mahogany box
£ 2-2-0” ; and “ 16 April, 1793. 2 ivory scale thermometers 16" long, divided into
tenths £ 6-6-0.” Some of these thermometers can be identified in the chest, Cat. 200.
The bill was sent to Van Marum by Edward Nairne with an accompanying letter,
dated 9 August, 1793. Here he explained that the partnership had been dissolved on
24 July, and that, as he was continuing the business, all debts were due to him.
He said that there had been a misunderstanding about the thermometers, which
Blunt had not told him about, and they would be credited if returned.
Van Marum had shown an early interest in this subject, because he mentioned
Crawford’s theories of heat, which were first published in 1779, in a letter to
Magellan of 24 May, 1784 (see Carvalho).
Crawford (1788) 177—188, II, an illustration of the complete apparatus; Carvalho
(1951) 196-198; Fox (1971).
Inv. 51/2
220 FIRE SYRINGE */4 19th C. (208) Fig. 195
Overall length closed 305, length of visible glass tube 210, tube diameter 20; length
of piston rod 240, length of piston 40, diameter 8.
A thick glass tube (now cracked) with brass ferrules, holds a steel-shafted piston,
made up of ten leather disks, that slides in the bore of the tube. The end-knobs are
made of boxwood. The knob screwed into the ferrule bears against a leather washer,
and when removed reveals a small hole to the piston chamber that can hold tinder.
The fire syringe works by rapidly compressing the air in the bore of the tube,
which is achieved by pressing or striking the piston rod as vigorously as possible. So
much heat is evolved that a flash of light may be seen accompanying the ignition
of tinder. In this model the tube is made of glass to show the flash of light.
220 riK. i9.
221
The effect on which the fire syringe is based was discovered accidentally by a
workman at the armoury in Saint-Étienne in 1802. He noticed that a piece of linen
stuck in the exit tube of the pressure syringe of an air gun (see Cat. 146) caught
light. The same workman noticed that a flash of light, possibly the ignition of oil or
dust, was produced when an air gun was discharged in the dark. These two effects
were communicated to the Académie at Lyons on 29 December, 1802, by Joseph
Mollet. Commercial production was started by the Parisian firm of Dumotiez in
1805, and it is thought that these instruments were similar to the one patented in
London by Richard Lorentz on 5 February, 1807, no. 3007, “ to produce instantaneous
light and instantaneous fire” . His products were unusual for the length of
piston stroke, some twelve inches, and for the compressed air passing through a
narrow hole before reaching the tinder. It may be that the present specimen was
made in London to Lorentz’s design. A very similar glass-tubed fire syringe was
advertised in 1848 by the American firm of Benjamin Pike for $ 6.00. Baird &
Tatlock sold a glass “ Pneumatic Fire Syringe” in 1928 for £ 1-15-0.
Accum (1808); Pike (1848) ii, 95; Baird & Tatlock (1924) 269; Fox (1969). For the
application of the principle in the American powder ram, see Ganot (1881) 41 jf.
221 FIRE SYRINGE ‘4 19th C. (209) Fig. 195
Overall length closed 230, length of piston chamber 185, diameter 14; length of
piston rod 190, length of piston 40, diameter 12.
This instrument, made of brass with a steel-shafted leather piston, operates in a
similar manner to that described above, Cat. 220, but now the intention is to
produce only lighted tinder. This model is unique among fire syringes preserved in
museums in that the tinder is contained in a turncock, so that bv a quarter turn
of the tap the glowing tinder is quickly revealed for use. In the most common type
of fire syringe the tinder is contained in the end of the piston, which has, therefore,
to be withdrawn after the compression. This type was patented, and manufactured
from 1806, by Dubois of Lyons.
For references see Cat. 220.
222 HEAT SYRINGE ,If4 igthC. (1138)
Overall height 420, base diameter 113, cylinder length 300, diameter 55.
The cylinder of the pump is made of thick brass; the rod of the piston ends in a
disk of mahogany, so forming the base. When the piston is forced hard into the
cylinder, the air so compressed produces heat. The principle is the same as in the
fire syringe, see Cat. 220.