PAET 3 .] 
Mallet: Blowing-Machines used in Upper Assam. 
153 
without interest. In India, although the forms of apparatus vary greatly in different parts 
of the country, they are, I believe, all modifications of the bellows, the supply of air 
depending on the alternate expansion and contraction of one or a pair of vessels constructed, 
wholly or in part, of a flexible material, like leather or raw skin. The contrivances used 
in Upper Assam are blowing cylinders, made of rigid material. Some machines have a 
double-acting single cylinder; others, a. pair of single-acting cylinders. The first of these 
is the form most commonly used, and may, therefore, be given precedence. 
The cylinder (aa, plate I), about 3 feet long by 10 inches diameter and three-fourth? of an 
inch thick, is cut out of a solid piece of wood; the excavation of the interior, as well as the shaping 
of the outside, being done with the ordinary simple tools possessed by the villagers. I have 
never seen any cylinders which had been turned or bored. Into the ends, disks of wood are 
fitted by rough dove-tailing (hb), the circular joints between disks and cylinder being ren¬ 
dered air-tight with clay. In the centre of one disk is a small hole in which the piston- 
rod (c) works. The latter is generally made from a slip of bamboo split from a large-sized 
piece, and has a diameter of, perhaps, three-eighths of an inch. At one end is a cross-handle ( d); 
at the other, the piston ( e ) : this is a disk of wood somewhat smaller in diameter than the cylinder 
and having a groove cut in the circumference, into which strips of skin from the necks of 
cocks are sewn by twine passing through holes for the purpose in the edge of the piston. 
The long, soft feathers fill up the space between the piston and cylinder, and produce but 
little friction, while not allowing much air to pass through. Bags are also sometimes used for 
this purpose, but are less effective. In both the end disks there is a double orifice (/) fitted 
with a valve ( g ) opening inwards; the latter made of leather, or a couple of folds of stout 
paper, fastened at one side by a slip of wood nailed to the disk. The object of the orifice 
being double is, that the division in the middle may give support to the valve, and prevent it 
being forced out by the presence of the air when the piston is approaching it. 
Close to each end of the cylinder there is a hole (/») of an inch or so in diameter, 
which allows the air to pass into the tubes (it). These are semicircular channels, cut in a 
piece of wood (j) of nearly the same length as the cylinder, to the side of which it is' nailed. 
As the channels approach each other, they bend round and end in circular orifices (Is), into 
which are fixed two bamboo blast-pipes (J), approaching each other at an angle of about 
20 degrees. These reach some way into the tuyere (m), which penetrates a clay screen (>i), the 
use of which is to protect the blowing-machine from the heat of the charcoal fire (o). The 
cylinder is generally supported on a couple of pieces of wood (p), so as to give the blast-pipes 
sufficient downward inclination. It is securely fixed by a stake (g) at each end driven into 
the ground. 
In using the machine, a man sits on the ground, and grasping the handle (d), works the 
piston backwards and forwards with a stroke of about two feet. When pulling, the valve (g 1 ) 
opens and admits air into the cylinder, while (g-) shuts, so that the entire blast is driven 
through the pipe (P). In pushing, the action is, of course, reversed. The two defects of 
the machine, are, that at the end of each stroke there is a momentary cessation of blast, and 
that a ceitaiu proportion of the air drawn into the cylinder is supplied by a return 
draft through the pipo (P), which somewhat diminishes the force of the blast 
into the fire from (I s ). The former defect could be remedied by adding an air-chamber, of 
sufficient capacity to steady the blast, between the pipes ( l ) and the screen, one pipe of larger 
diameter than (/) projecting from the air-chamber into the tuyere. The latter defect could be 
obviated by closing the holes (It) or the pipes (/) with valves opening outwards.* In practice, 
however, neither defect is of much consequence, as the machine, as it stands, answers the 
* This defect, and its remedy, has been already pointed out by Mr. Medlieott.— Methoire, Geological Survey 
of India, Vol. IV, £.413. 
