al system is to write with an ink having a somewhat viscid character, and to expose the written page to pressure in contact with a leaf of bibulous paper.
One of the first suggestions in this line was by Benjamin Franklin, who sanded the yet wet ink of the manuscript, passed it between rollers in contact with a polished soft-metal plate, imbedding the emery in the pewter so as to leave an impression from which a copy may be obtained by the copperplate printing process.
James Watt, about 1780, adopted the plan of pressure of a page of bibulous paper against the damp manuscript, the writing being legible through the thin copyingpaper.
Ritchie's copying-press A has formed the model for most of its class, having a bed, a platen, and a cam-lever.
The book containing the manuscript in contact with a damp page, is placed on the bed, and the platen p brought down by the rotation of the nut h, which traverses the screw s. An effective pressure is then brought to
ong textile fabric of hemp or flax, known as burlaps. It is woven of a width of from four to eight yards. The pieces of convenient size are stretched in a vertical frame, and size is applied by workmen who stand on ranges of scaffolding in front of the canvas.
It is pumice-stoned to remove asperities.
The color for the back is a thick paint laid on with a peculiar trowel.
The front is then sized, pumiced, and receives several coats of paint.
The pattern was at first stenciled, but since 1780 has been put on with blocks about 18 inches square, one for each color, and the blocks register with each other as in calico-printing or paper-staining.
The canvas is spread upon a large table.
Each block in turn is dipped face downward upon a cushion wetted with paint of the particular color for that block.
A layer of paint is thus taken up and transferred to the canvas, as in printing.
The colors are applied one by one, occupying their proper places in the pattern, which is made of litt
he United States, and still maintains its ground for some purposes.
Leathern hose was first sewn with waxed twine, then copper wire was substituted, and finally riveting.
Leathern hose, made in detachable sections, for application to fire-engines, was invented by Heide, a Dutchman, in 1672, and was common in the Netherlands soon after.
The spiral coil of wire inserted throughout the length of suction-hose, to keep it from collapsing, was used with the Newsham fire-engine, London, about 1780.
Rubber hose is made by wrapping rubber-cloth (which see) around a tube of the required size, the number of plies depending upon the required strength.
The tube is then placed in a heater and subjected, for a sufficient time, to a steam pressure of 80 pounds to the square inch = 289° F., which melts the sulphur and vulcanizes the gum.
The tube is then withdrawn from the hose.
Or a sheet of rubber wrapped on a tube and covered by several webs of cloth, saturated with prepared rubber,
x, the crank.
y, the side-frame, firmly secured to the bed-plate, and to strong flanges east on the cylinder.
z, the guides in which the cross-head moves.
The lever-escapement was invented by Mudge about 1780, and improved by Breguet of Paris and Roskell of Liverpool.
In its first form, the end of the lever had a segment-rack which engaged a pinion on the arbor of the balance. The improved form consisted in substituting a fork for the rack, making wbstituted.
The smoke rose through an opening 18 inches in diameter in the dome of the lantern, passed into a finial chamber above, and escaped by side openings.
In 1727, the lantern was destroyed, and an iron one substituted by M. Betri.
In 1780, the catoptric system of lighting was introduced by Borda, an Argand burner being placed in the focus of a parabolic mirror formed of copper plated with silver.
The focal length was about 4 inches, the diameter of the outer edge 21 inches. The be
tglass micrometer, which was more perfectly adapted by Bouguer, seventy years afterwards.
Boscovich, in 1740, invented the circular micrometer, which was used by Lecaille in 1742, and Olbers, 1798, and improved by Frauenhofer.
Ramsden, about 1780, suggested the use of cobwebs as a fine filament substitute for wire.
It has been credited to Troughton.
A substitute for the spider-line micrometer, over which it possesses many advantages, is formed of a thin plate of glass on which equidiste, from its producing yarn finer and softer than was obtained from any other machine then known, more nearly to the standard of the India muslins, which are yet the admiration of the cotton-trade.
Crompton gave up his invention to the public in 1780. Thirty-two years afterward he received pound5,000 from government as a compensation for his services.
This was unfortunately frittered away in starting his sons in business, and the father was again in poverty.
A subscription was raised for him
msey obtained a patent in England for a mode of propulsion of vessels by the force of water ejected by a steam-pump.
In 1780, Watt suggested the spiral oar to move canal-boats.
In 1780, the present arrangement of connecting-rod crank and fly-wh1780, the present arrangement of connecting-rod crank and fly-wheel was patented.
In the same year the Marquis de Jouffroy worked a steamboat 140 feet long on the Saone.
In 1782, Rumsey propelled a freight-boat on the Potomac by means of the hydraulic propeller.
A steam-engine worked a vertical pump amidshipng steam and water pipes.
The puddling-furnace was invented by an iron-master of the name of Henry Cort, about the year 1780, the bed of whose furnace was made of sand, consequently the carburet was refined, many of its impurities, especially the the form of a simple metallic bar, about 1730.
The first which ever came into extensive use was that of Wedgwood, about 1780; it was devised and used by him for testing the heat of his pottery and porcelain kilns.
No fewer than eleven different
h are continued all the way around its limb, thus embrace 720° of are.
It was first invented by Mayer about 1744.
Borda, after whom it is frequently called, in 1780, introduced a second arm and vernier, to which Troughton subsequently added a third.
The mean of the readings given by each arm is taken as the true angular measpread of what would throw so many mechanics out of employment.
It was prohibited in Holland for that reason in 1623.
It is first noticed in England in 1674.
In 1780, the mode of ornamentation (watering) by pressing between figured steel plates was adopted.
Steel cylin- ders were afterward substituted.
See narrow-ware loom. a in addition to the day's work, a certain amount of hulling being performed by each before regular work and after it.
Machinery was constructed by Lucas, about 1780-90, which was driven by tidepower, and operated iron-shod pestles in cast-iron mortars of the capacity of five bushels each.
Steam-power was subsequently introduc
idships, over the keel, or alongside; twin screws at each side of the dead-wood at the stern.
In the early applications of the screw as a propeller it consisted of a spiral blade, which made one convolution around its stem.
Then two halfcon-volutions of a double-threaded screw were used.
Since that time the tendency has been to reduce the length of the spiral.
We find notices of the suggested or experimental use of the screw-propeller by Hooke, 1680; Duquet, 1727; Pancton, 1768; Watt, 1780; Seguin, 1792; Fulton, 1794; Cartwright, 1798; Shorter, 1802.
The idea of propelling vessels by a screw in lieu of oars is mentioned in the Machines et Inventions approuvees par l'academie Royale des Sciences depuis 1727 jusqu à 1731.
Franklin suggested the same thing.
Lyttleton's English patent, in 1794, for an aquatic propeller consisted of a screw of one, two, or more threads wrapped around a cylinder, and revolving in a frame placed at the head, stern, or side of a vessel.
rs variously engraved, which, bearing unequally upon the stuff, render the surface unequal, so as to reflect the light differently.
Watering silk is said to have been invented by Octavius May, at Lyons, seventeenth century.
See moire, etc.
In 1780, the mode of ornamentation was by pressing between figured steel plates.
Steel cylinders were introduced afterward.
Moire silk for watering is made of double width, which is indispensable in obtaining the bold waterings, for these depend not oing.
The dissolving of lead in vinegar to make a pigment was known to the ancients.
Various methods have been and are used in its manufacture.
By the Dutch process, generally employed in England, where the manufacture was introduced about 1780, metallic lead cast in star or circular shaped gratings 6 or 8 inches in diameter is placed in pots containing strong acetic acid, over, but not in contact with, the acid.
The pots are imbedded in a mixture of new and spent tan, and are covered w