Mr. Dent, in a lecture delivered before the London Royal Institute, made an allusion to the formation of a watch, and stated that a watch consists of 992 pieces; and that 40 trades, and probably 215 persons are employed in making one of these little machines. The iron of which the balance wheel is formed, is valued at something less than a farthing; this produces an ounce of steel, worth 4 1-2 pence, which is drawn into 2,250 yards of steel wire, and represents in the market, 13_l._ 3_s._; but still another process of hardening this originally a farthing's worth of iron, renders it workable into 7,050 balance springs, which will realize, at the common price, of 2_s._ 6_d_ each 746_l_. 5_s_, the effect of labor alone. Thus it may be seen that the mere labor bestowed upon one farthing's worth of iron, gives it the value of 950_l._ 5_s_, or $4,552, which is 75,680 times its original value. =Mule Boats.= This kind of conveyance is, we believe, peculiar to the Illinois River, for we never remember to have seen one belonging to any other stream. A year or two since, we were perfectly astonished at beholding the first one that ever arrived in this port; but now they are as common as the species usually termed _broad horns_, and their appearance creates about as much surprise and curiosity among the more aristocratic order of steam and sail. A genuine mule boat is not unlike an ocean steamer, as they are susceptible of being propelled both by steam and wind; with this difference, the mule-boat steam is generated upon the tread-mill plan, and by the united exertions of some half dozen quadrupeds, generally of the long-eared kind. To this treading or pulling apparatus are attached cylinder, pitt-man, boilers, &c., in the shape of some three or more cog-wheels, and immediately connected with them is a couple of shafts, which give a rotary motion to a couple of water-wheels, one on each side, and which usually propel a keel about 100 feet in length, and of about 75 tons burthen; over it is a roof and covering, usually called a cargo box, to protect the inside from the weather, and the whole making an appearance similar to an Ohio river keel boat, with the exception of a space left her to operate in. The difficulty and danger attending the management of a boat propelled by steam, is upon the mule boat entirely dispensed with.