er several hours.
It is strapped to the dress, and communicates with the interior of the latter by a pipe which has a faucet.
Expansible bags are attached to the shoulders, which are made buoyant by inflation from the compressed-air reservoir when required.
The air-knapsack is weighted so as to enable the diver to sink to his work.
The air-tube enters the mask at a point over the ear. The artist has made rather a close fit of the dress and mask, and the effect is rather too cherubic.
Hawkins's mouthpiece for diving apparatus.
In Fig. 360 is shown a respirator designed to be attached to the helmet of the diver whereby air is supplied from a forcepump in the vessel which floats on the surface of the water.
It has an induction and an eduction valve, which both open in the same direction, giving way respectively to the blast of fresh air and to the force of the exhaled breath.
While the breath is being inspired by the diver the induction-valve is open to admit fresh air, and
of London, built a machine that carved medallions and figures in ivory and ebony, producing some very handsome work with great rapidity; in 1814 and 1815, Mr. John Isaac Hawkins, of the same city, produced a similar machine for the same purposes; in 1828, a Mr. Cheverton built a machine for similar purposes, the operations of whivented by Wedgwood, 1806, and consisting of colored sheets alternating with thin paper, and giving a number of identical impressions by the action of a stylus.
Hawkins's polygraph, in which several pencils are carried in a frame, each obeying the action of a principal and writing upon its own particular sheet of paper.
Copyinth century burnt seven floating mills on a stream in Bulgaria,— a pretty fair specimen of the crusading rabble.
The current-wheel of Belisarius was patented by Hawkins in England in 1802, and by several other parties before and since, both there and here.
（Telegraphy.) A device
by cord f over small wheel e, float-wheel d, and pulley c.
A double or treble tree, to even or divide the work of pulling upon the respective horses.
It is swiveled to the pole, usually by a bolt or wagon hammer, and has clips on the ends to which the middle clips of the single trees are attached.
A pencil-case having a fine cylinder of graphite, which is brought forward by a screw as fast as wear renders it necessary.
Patented by Hawkins and Mordan, England, 1823.
The pencil-case has a slider actuated by a screw to project a little cylinder of black-lead as the latter wears away.
The lead is so small in diameter that it does not need cutting for the ordinary purposes of a pencil.
The projection of the lead is performed by holding the nozzle in one hand and turning round the pencil-case with the other.
A reservoir at the end of the holder contains a supply of spare leads.
A toilet-pitcher with a wid
ed down with great rapidity, the gold catching, as has been observed, in the interstices between the blocks which form the floor of the sluice.
A pen with a gold nib pointed with rhodium or iridium.
In 1823, Hawkins and Mordan (English) made tortoise-shell and horn nibs with diamond and ruby points.
These were followed by plates of gold attached to the tortoise-shell nibs.
Doughty's pens were of gold with ruby points.
Wollaston's pens were of two flain 1817 Deakin attached a metallic box, holding fuel for one day's consumption, to the back of the fireplace; the fuel was drawn forward horizontally by a screw, as required, and in this way the smoke was nearly all consumed.
In the same year Hawkins patented a shovel for supplying coal to the fire at bottom.
The shovel had a cover, and the contained coal was pushed forward into the fire by a piston.
The revolving grate was introduced by Steel and Brunton, English patents, about 1819.
ical instrument which shows the inside of the eye. Used to detect foreign substances and diseases.
Equivalent, 99; symbol, Ir.; specific gravity, 22; nearly infusible.
It is a white, hard, brittle metal, more difficult to fuse than platinum, and the heaviest of all known substances.
It has been used for forming the tips of gold pens.
The alloy of iridium and osmium, called iridosmine, is the hardest of all alloys.
It forms the point of the everlasting pen, made by Hawkins of England, and is ground by diamond-dust.
An alloy of iridium and osmium.
The hardest of all known alloys.
An instrument contrived by Dr. Reade for exhibiting the prismatic colors.
Sir David Brewster describes it in the Phil. Trans.
for 1841 as a plate of polished black glass, having its surface smeared with a solution of soap and dried by wash — leather.
On breathing through a tube upon the glass, the vapor is deposited in brilliant colored rings.
nto pens and adapted to be placed in a holder.
These were, perhaps, the first nibs, the progenitors of a host of steel, gold, and other pens.
Hawkins and Mordan, in 1823, made nibs of horn and tortoiseshell, instead of quill.
The tortoise-shell being softened, points of ruby and diamond were imbedded.
Metallier is socketed in the other end, either projecting for use or inclosed for compactness in carryinging.
The ever-point pencil was patented in England in 1823 by Hawkins and Mordan.
The small cylinder of black-lead is pushed forward by a driver, so as to project through the end of the nozzle.
On the outside of the driver is a nd.
1. An instrument for making a number of drawings or writings simultaneously.
It is on the principle of the pantograph, and was invented by Hawkins (English).
A number of pencils are placed in a framework of jointed rods, so arranged that each subordinate one partakes of the motion of the principal one, wh