"Twenty pounds of beef suet rendered;

"One gallon of neats-foot oil;

"One pound of pitch: "Three pounds of black resin.

"These two last articles must be previously melted together, and then added to the other ingredients; when the whole must be heated in a proper iron vessel, with a close cover fitted to it, until the moisture is entirely evaporated. and the compolose their hardening property after a few weeks' constant use; the saws are heated in long furnaces, and then immersed horizontally and edgeways in a long trough containing the composition; two troughs are commonly used, the one until it gets too warm, then the other for a period, and so on alternately. Part of the composition is wiped off the saws with a piece of leather, when they are removed from the trough, and they are heated one by one over a clear coke fire, until the grease inflames; this is called "blazing off." When the saws are wanted to be rather hard, but little of the grease is burned off; when milder, a larger portion; and for a spring temper, the whole is allowed to burn away. When the work is thick, or irregularly thick and thin, as in some springs, a second and third dose is burned off, to ensure equality of temper at all parts alike.*

Springs and saws appear to lose their elasticity, after hardening and tempering, from the reduction and friction they undergo in grinding and polishing. Towards the conclusion of the manufacture, the elasticity of the saw is restored principally by hammering, and partly by heating it over a clear coke fire to a straw colour; the tint is removed by very diluted muriatic acid; after which the saws are well washed in plain water and dried.

Watch springs are hammered out of round steel wire, of suitable diameter, until they fill the gage for width, which at the same time ensures equality of thickness: the holes are punched in their extremities, and they are trimmed on the edge with a smooth file; the springs are then tied up with binding-wire in a loose open coil, and heated over a charcoal fire upon a perforated revolving plate; they are hardened in oil, and blazed off.

The spring is now distended in a long metal frame, similar to that used for a saw-blade, and ground and polished with emery, and oil, between lead blocks; by this time its elasticity appears quite lost, and it may be bent in any direction; its elasticity is, however, entirely restored by a subsequent hammering on a very bright anvil, which "puts the nature into the spring." sition will take fire on a naming body being presented to its surface, but which must be instantly extinguished again by putting on the cover of the vessel." - Manufactures in Metal, Vol. i. p. 336. Lardner's Cyclopaedia. See also page 311, Ibid.

* Gun-lock springs are sometimes literally fried in oil for a considerable time over a fire in an iron tray; the thick parts are then sure to be sufficiently reduced, and the thin parts do not become the more softened from the continuance of the blazing heat.

The colouring is done over a flat plate of iron, or hood, under which a little spirit lamp is kept burning; the spring is continually drawn backwards and forwards, about two or three inches at a tunc, until it assumes the orange or deep blue tint throgh-nut, according to the taste of the purchaser; by many the colouring is considered to be a matter of ornament, and not essential. The last process is to coil the spring into the spiral form, that it may enter the barrel in which it is to be contained: this is done by a tool, with a small axis and winch handle, and does not require heat.

The balance springs of marine chronometers which are in the form of a screw, are wound into the square thread of a screw of the appropriate diameter and coarseness; the two ends of the spring are retained by side-screws, and the whole is carefully enveloped in platinum-foil, and tightly bound with wire. The mass is next heated in a piece of gun-barrel closed at the one end, and plunged into oil, which hardens the spring almost without discolouring it, owing to the exclusion of the air by the close platinum covering, which is now removed, and the spring is let down to the blue, before removal from the screwed block.

The balance or hair-springs of common watches are frequently left soft; those of the best watches are hardened in the coil upon the plain cylinder, and are then curled into the spiral form between the edge of a blunt knife and the thumb, the same as in curling up a narrow riband of paper, or the filaments of an ostrich feather.

Mr. Dent says that 3,200 balance springs weigh only one ounce; * but springs also include the heaviest examples of hardened steel works uncombined with iron: for example, of Mr. Adams' patent bow-springs for all kinds of vehicles, some in-tended for railway use, measure 3 1/2 feet long, and weigh 50 pounds each piece; two of these are used in combination; other single springs arc 6 feet long, and weigh 70 pounds.†

In handening thorn they are heated by being drawn backwards and forwards through an ordinary forge fire, built hollow, and they are immersed in a trough of plain water; in tempering them they are heated until the black red is just visible at night; by daylight the heat is denoted by its making a piece of wood sparkle when rubbed on the spring, which is then allowed to cool in the air. The metal is nine-sixteenths of an inch thick, and Mr. Adams considers five-eighths the limit to which steel will harden properly, that is sufficiently alike to serve as a spring; he tests their elasticity far beyond their intended range.*

* The raft springs are worth 2s. 6d. each; the hardened and tampered springe, 10s. 6d each. This raiaes the value of the steel, originally leas than twopence, to 400l. and 1600l respectively. - Mr. Deaf's Lectures on Time-pieces, &c

† The principle of theas bow springs will be immediately teen, by conceiving the common archery bow fixed horizontally with its cord upwards; the body of the carriage been attached to the cord sways both perpendicularly and sideways with perfect freedom.