breadth 16, side walls 8 feet, with a pavilion roof of the

common range.

The work performed here was the filling of about 150 pairs of moulds, of all sizes, three times each day. These occupied the floor of brick in different ranges, and presented a very large aggregate of heated surface when poured. The quantity of metal thus formed into shot at each cast was nearly a ton. In May 1796 the average temperature of this workshop for several days during casting was 115° Fahr. One day a spirit-of-wine thermometer burst in my hand with a report like a pistol. Its greatest range of scale was 120°: the passages betwixt the moulds, for the movements of the pourers, were 130°. In all these extra temperatures I uniformly observed that a considerable portion of the shot, particularly in the third cast, passed the gauge with difficulty, and many of these found unserviceable for carronades, where the windage allowed upon the calibre of the piece is less. In the middle of August in the same year, during a period of very hot close weather, I made repeated trials, and found the effects always proportioned to the temperature of the workshop. I shall finish this paper with the particulars of one day's observations.

Greatest heat in 35 minutes being three

minutes after the pouring had ceased, 156

From 128 to 156o I felt a sensation of cold similar to that when approaching a fire in winter, accompanied by a considerable degree of shivering. About 150 this sensation wore off, and I felt comparatively comfortable. Per

spiration had now become so violent as to ooze through all parts of my waistcoat, breeches, and stockings. The workmen who carried the metal perspired in such a manner as to wet their large sacking trousers as if they had been soaked in water. The moisture ran in such torrents from their faces and arms, as to be distinctly heard hissing upon the heated moulds. Their step and arms were more agitated than I had ever before observed, and the sinews all over their bodies were uncommonly large, and felt inflated to a great degree. Two men performed the whole labour of pouring; so that each of them in 32 minutes carried half a ton of metal in quantities, in hand-ladles, from forty to fifty pounds each time. The space gone through each time, the return with the empty ladle included, was nearly 120 feet, or fully equal, upon the whole travel, to half an English mile: the half of which space was traversed with a ladle, metal included, weighing 80 pounds. One of the men, immediately after this operation, emptied a pitcher of spring water at one draught which I estimated at five English pints.

The phænomena of the 2d cast were not so marked. So much is the human body the child of habit, that I neither felt the same extent of sensation, nor remarked it upon the workmen, although the thermometer maintained itself for some minutes at 158°. In the afternoon the air began to circulate, and the temperature of the shop became much more moderate. The third cast, however, soon destroyed this pleasant change, and, before half done, the thermometer rose to 164°. Still the workmen seemed to suffer less than in the morning, except on the legs. Most of the ranges of large moulds were throwing off the caloric in ruelle undulations, and exhibiting symptoms of approaching redness. The smallness of the shop admitted only of 2 1-2 feet of passage betwixt range and range; which made the temperature of this spot intolerable.

When the cast was finished I had the doors and windows shut. This made the real state of the moulds visible. The 18, 24, and 32-pounders were all of a dark glowing red heat, and presented an arid and inhospitable glare with which it was impossible long to exist.

Some Account of the Manufacture of Forged Iron Vessels, at Fromont. By M. CH. HERSART.*

THE operations of forging vessels of cast iron may be divided into three distinct parts: 1st, the method of forging the plates; 2d, that of forging the cake or parcel; 3rd, the cold hammering. Of these we shall speak in the order here mentioned, which is likewise the order of fabrica

tion.

To Forge the Plates.-The iron for this manufactory must be very soft and malleable. It has usually the form of bars, ten or twelve feet long; each bar having the form of a long truncated square pyramid. This form is necessary in order to obtain plates of different diameter. The small base is a square of ten lines, or twelfths of an inch, and the greater eighteen lines.

The assistant puts one of these bars in the fire, and when the heated part is ignited, the master forgeman carries it to the small tilting hammer, which is not different from those used in drawing out steel bars. He places the bar on the anvil, not upon one of its faces, but on an edge, as, in this position, the iron is less subject to crack. Accord. ing to the size of the plate intended to be hammered out, the workman strikes a greater or less portion of the bar, presenting it in all situations to the hammer, in order that the plate may obtain a circular form. Between the plate

* Journal des Mines, No. 113.

and the bar itself, he fashions a small neck to facilitate its separation. In this manner, the workman continues to forge the plate on both its faces as long as the heat allows, after which he carries the bar to the anvil, and applies a cold chissel to the neck, upon which his assistant strikes in order to separate the plate from the bar. This last is then returned to the fire, in order to continue the operation in making a second plate. Sometimes, but this is only when the plates are small, the workmen make three at

once.

魯

When a sufficient number of plates has been thus fabricated, as they are of different sizes, namely, from three or four inches diameter to a foot, the workman disposes them in parcels, of which each contains four of equal dimensions, and then carries one of them to the hearth of the furnace, where the assistant takes them in the large tongs, Fig. 1, Pl. VI, and puts them into the fire, taking care to change their position often; and when the brass is red hot, the master workman, who holds a small pair of tongs in each hand, carries it under the tilting hammer, after having spread charcoal powder between the plates, to prevent their welding together. The two pair of small tongs have the form of Fig. 2 and are used to give a cir cular motion to the parcel, and to keep it on the anvil. When he has finished hammering it, he changes the or der of the four plates, and in making this change, he is careful to take notice whether any of them have cracked; and where he perceives any crack, he applies the cold chisel, or a wedge to the place on which the assistant gives a blow.

After having changed the situation of the plates in such a manner that the two outside plates become the interior ones, he places this parcel on the hearth, and takes another set, which the assistant has caused to be heated, and he subjects this to the same operation of the hammer. In