The expression of the vegetable oils, was found to be the most difficult operation to be performed, by instruments of this sort, and it is probable, that it was to effect it, that machinery, by which increased force might be employed, was first made use of.Oil mills, of this sort, are yet common in the east.
This construction rendered the union of the wooden mortar and pestle, with the parallel instrument of stone, almost inevitable.Hardness and heaviness, being the requisites in the pestle, and an equal resistance being necessary in the mortar, to bring about the junction, it would seem to have been only requisite, that the two machines should have met where there was a scarcity of wood of proper quality.The handle of the pestle, through which a cross bar was then thrust, became the axle of the upper mill stone, and the lower mill stone formed the bottom of the mortar.The movement then became altogether circular, and required small absolute force, but as much swiftness as could be given to it.The machine thus generated, by the passage of the one instrument into the other, was then a regular mill, to work which was the employment of cattle or slaves.As it united the advantages of the two original instruments, the.capacity of the wood to receive and modify motion, and of the stone to braise and comminute hard vegetable matters, its invention seems to have had considerable effect in advancing art still farther.The moving power, in one of the most laborious and common operations, was thus reduced to a simplicity of action, that paved the way for its being performed by an inanimate agent; such an agent was introduced into the process, through the intervention of another art.
In hot regions, water is very abundantly consumed, both as a necessity and luxury, for immediate use, and as the great fertilizer of the soil.
In such regions, the raising it from wells and rivers has always been a very common and laborious process, and to facilitate it has given occasion to some of the earliest efforts of ingenuity.One of these consisted of a large wheel, placed upright, and to the circumference of which small buckets were affixed.It was put in motion by treading on it, and the buckets and it were so arranged, that they should just dip beneath the stream, in the lower part of their circumvolution, and, at the height of it, should empty themselves into a reservoir placed above.A considerable saving of labor was thus produced.Another improvement did entirely away with the necessity of employing it, in many situations.To the outside of the wheel, wlmre there was a sufficient current, were affixed broad plates of wood, or other material, on which the strength of the stream acting, forced it round, and performed the office of the laborer.Such engines are of common use in China, at present.They were known in Italy, in the time of Julius Caesar, to which they probably found their way from Asia.They presented to the Romans a means of employing the power of water in the laborious operation of grinding, (72) which they had sufficient discernment to adopt.The motion of the water-wheel, was communicated to the mill by the intervention of a toothed wheel.
Thus, from the union of the productions of the inventive faculty exercised on at least three arts, came the rude model of the present water-mill.
Its progress was at first slow.Such mills, seem only to have been constructed, when there was a current of water suited to the purpose.The expense of forming artificial falls, seems to have been too great for the improvidence of the age.Though abundant materials existed, the accumulative principle of the people was too weak to work upon them.Cattle-mills, and mills driven by slaves, continued therefore to be generally preferred.(73) It was owing to an invention, like so many others, the result of necessity and genius united, that the use of water-mills became more general.When Rome was besieged by the Goths, in the time of Belisarius, they cut off the supply of water by the aqueducts.Among the other inconveniences arising from the measure, it stopped the mills driven by the water from these aqueducts.
To remedy the evil, that general devised the scheme, of anchoring barges in the river, in which he placed mills driven by the current.The plan met the immediate exigence, and, as such a construction suited the low strength of the accumulative principle of the age, it was generally adopted elsewhere.In the present times, such a plan would be rejected, because, though the first expense is comparatively small, the durability of the instrument is too short.We prefer the greater expense of making dams, and sluices, on account of their greater durability.The cause leading to the construction of the one or the other, is the same as that determining the Chinese to the formation of floating gardens, where the Dutch would build dams.
The invention maintained itself through the dark ages, and followed the improvement and extension of agriculture, and facility of communication, which returning civilization and tranquillity gradually diffused.It seems to have spread very generally over Europe, about the beginning of the sixteenth century.The force of water being, by it, turned to the service of man, wind also was made to employ its powers to a similar purpose.
