The hammermen are paid for other pieces as follows:

Shafts, per quintal,
Cart axles,"

$1.00

.50

Cost of One Ton of Puddled Bar Iron, Shingled by Steam Hammer.

This estimate is based on the few weeks' work of the double puddling furnace.

Cost of One Ton of Ordinary Bar Iron, Rolled from Billets.

1.045 tons of billets @ $52.03,

Packing from bloomary to mill,

Heating (labor), .

Heating (fuel, 6 cartloads wood, 334 cubic feet, @95 cents),

4.50

5.00

.68

.50

2.50

$69.58

Cost of One Ton of Ordinary Bar Iron, Rolled from Puddle Bar.

1.045 tons puddle bar, @ $34.00,
Heating, rolling, etc.,

$35.53

14.18

$49.71

From the notes of Mr. Michael O'Neil, an experienced puddler from Bethlehem, Pennsylvania, I gather the following, which is added as an interesting description of the condition of the works. He found the small puddling furnace choked up and that it had been used for melting brass. After making proper repairs, using the refractory stone of the country, which he was assured was "perfectly infusible," it was started. The charges were first 350 pounds of iron, and, finally, 450 pounds; the iron melted in three quarters

of an hour, and each heat lasted about an hour and a half; here a heat usually takes from two to two and a quarter hours. The iron was very dry, but with plenty of good dry wood it worked perfectly. Balls of only 80 to 100 pounds were made, and shingled under a small trip-hammer of two and a half inch face. After every two or three heats, delays occurred on account of portions of the roof and stack melting down, which would have to be removed. Two entire new roofs of the "refractory" stone were built from Nov. 1st to Jan. 31st, when so much of the stack fell that it was deemed useless to repair it, and puddling was postponed for a time.

The time from February until May was consumed in building the heating furnace. The refractory stone was again used, the roof was twelve inches thick, and would last about three weeks, single turn, but the chimney, after three days, melted so much as to entirely fill the take-up and stop operations; it was then lined with fire-brick, and has worked well ever since. The charge was 800 to 1200 pounds, according to the size of the billets, and took three-quarters of an hour to heat.

The double-puddling furnace was commenced in May, and completed about the middle of August. Here numerous drawbacks again occurred; from the contraction of the fire-brick; the bridge wall fell, damaging a portion of the fire-chamber. The wood was so wet that even though dried in strips on hot iron plates, it would scarcely burn, so that the grate-bars had to be altered to allow the addition of charcoal. The hands were green, and from their little knowledge previously gained at the small furnace, were very conceited and impertinent, considering themselves teachers rather than learners. The charges were 900 pounds, and six heats were made in eleven hours; the iron hammered under the steamhammer, worked well, and was of fair quality. Work continued about two weeks, when fifteen feet of the stack fell on account of the contraction of the fire-brick, a portion being constructed of key-brick; the work was then stopped.

Mr. O'Neil's contract expiring at this time he came home, after having taught them all he could in a year. It is much to be regretted that they did not learn more, or rather that they concluded that they had learned everything, and allowed him to return so soon. His salary, travelling expenses and maintenance, amounted to about $4000. One may judge of the cost of this experiment, which may be taken as a type of the cost and difficulty of introducing new things into this country. We refrain from estimating the cost per

ton of the iron he did puddle, but will mention the quality of that puddled in the small single furnace.

The usual Mexican test is to hammer a rod cold into a nail: this it stood perfectly. Specimens of this iron were exhibited at the Centennial Exhibition, and tested on Riehle's testing machine. The tensile strength per square inch was as follows: 53,880 pounds; 54,060 pounds; 54,700 pounds; 58,930 pounds; 58,590 pounds. The qualities of this iron are magnificent. Even with the present rude manufacture, it fully equals the special brands of European and American iron, manufactured with the greatest care and skill.

PRESENT PRODUCTION OF THE WORKS.

Active operations are carried on from the first of July to the first of May, ten months, or while the supply of water lasts. During this period the furnace is in blast about two hundred days, producing about 400 tons of pig iron and castings. The bloomary fires are active, off and on, all the time; but from stoppages on Sundays, Saint's days, and break-downs, they may be said to average three and a half weeks' actual work during the month, or thirty-five weeks for the year. Each bloomary produces 3 tons of billets a week, with a loss of iron of about 25 per cent. These three bloomaries, during the year, produced 315 tons of billets and consumed 394 tons of pig iron. The loss of heating and rolling billets into bar iron is 4 per cent., leaving a yield of 301 tons of bar iron. Castings are made direct from the blast furnace at a cost for patterns and moulding of threequarters of a cent. per pound, or $15 per ton; whence we have

We will assume that all the production is from furnace No. 2, the puddling furnaces and rolling mill, though for four months in the year, when there is an excess of water, furnace No. 1 and the bloomaries might be employed.

Assuming furnace No. 2 to be worked under the same conditions

as furnace No. 1 as regards ore, fuel, and labor, and that it produces ten tons of pig iron daily, the price of labor per ton will be reduced to $1.13, and it will then cost $16.03.

Supposing the furnace in blast 200 days per year at 10 tons per day,-2000 tons; of this is sold as castings, 500 tons, leaving to be puddled and rolled into bar iron, 1500 tons. Assume that the mill works 250 days a year, and each double-puddling furnace only produces 2 tons per day, or 500 tons per annum, then three puddling furnaces (allow one more for accidents), and two reheating furnaces will do the work. We have then as the production of the works the following:

Such is the condition of the manufacture of iron in this portion of Mexico, and it may be taken as a type of its manufacture in other parts of the republic.

It is obvious that the works were badly located in the beginning, and it is a question whether it would not have been more judicious, instead of adding to their new improvements, to have built an entirely new concern at the Tacotes Mine, using steam-power entirely.

While the large furnace is in full blast the daily transportation of 15 tons of ore from the Tacotes Mine, will require 210 mules and 35 mounted drivers, a day being allowed them to return. A wagon road will have to be constructed: then 6 wagons, 72 mules, and 12 drivers will do the work. Still these works possess advantages that few enjoy, and were their resources properly developed, they would make iron cheaper than anywhere in the world. They have the richest and purest of ores, that produce an iron only surpassed by the best from Sweden, abundance of cheap fuel, and superabundance of cheap labor. This last, however, is not an unalloyed blessing, for double the necessary number, and a host of decrepit old foremen are employed, and the "compadre" system all-powerfully reigns.

The market for the iron extends throughout the States of Colima, Michoacan, Jalisco, and Zacatecas; covering an area of more than 100,000 square miles of the richest and most enterprising part of the republic, and the works always have more orders than they can fill, at prices ranging from eight cents to ten cents per pound. There is a

slight competition from foreign iron in the towns near the coast, but as this has paid excessive duties and costs of transportation, it can be easily excluded by the really superior Tula iron, which can always undersell it.

There are many Catalan forges in the neighborhood operated by Indians, who eke out a meagre existence by selling, at three cents per pound, the plow-shares, axes, and billets they produce, to the shopkeepers, who advance them food. This manufacture does not amount to a competition; but a well-organized lot of forges throughout the country, and portable steam-engine and hammer to make nail-rods, which would require but very small capital, could offer very serious competition.

In the face of numerous difficulties, and after the expenditure of immense sums of money and indomitable energy and pluck, Tula has been established, and fully contributed its share to the advancement of the independence and civilization of the country.

THE ACTION OF SMALL SPHERES OF SOLIDS IN ASCENDING CURRENTS OF FLUIDS, AND IN FLUIDS AT REST. BY J. C. BARTLETT, A.M., CAMBRIDGE, MASS.

(Read at the Wilkes-Barre Meeting, May, 1877.)

THE following discussion was suggested by an experiment of Mr. Krom, the manufacturer of air-jigs, to illustrate the superiority of air over water as a medium of concentration. The paper is written in the interest of no system of concentration, but simply to test the experiment, and, perchance, to add something to the general fund of information on the subject.

To speak of testing an experiment by a theoretical discussion, may seem a misuse of terms, but the theories concerning falling bodies and the resistance of fluids are pretty well crystallized into laws, which may properly be used to show where experiments which seem to refute them were improperly performed, and that instead of refuting they only corroborate.

It is well known that a sphere of galena inch in diameter, and a sphere of quartz inch in diameter, are equal falling in water; that is, these two spheres, being placed together in a column of water at rest or in motion, will practically remain together, falling or rising together, or remaining in suspension. Mr. Krom, to show that these