MECHANICS. 
684 
Strand, London. It was to afcertain how far the draught 
of their heavy coal waggons up the itnmenfe fteep into 
the Strand, might be relieved by removing one pair of 
the horfes from the front to the hind part of the waggon. 
For this purpofe, a pair of (hafts reverfed were attached 
to the back of the carriage; and horfes who have hitherto 
been ufed to pull, were now, for the firlt time, feen to 
puffi the load before them. Thus a coal-waggon, with 
two horfes before and two behind, whereby the whole of 
the power is placed in fuch immediate contact with the 
weight, drew it along full as ealily as feven horfes have 
hitherto been acculfomed to do that work. 
Of WIND-MILLS. 
“The mechanifm of mills, particularly that of wind¬ 
mills, is one of the matter-pieces of human induftry.” 
Bojfnt, Hijt. des Malkematiques, Part I. ch. iv. 
Few people are ignorant that corn is ground by two 
mill-nones, placed one above the other, without touch¬ 
ing. The lower mill-ftone is immoveable, but the upper 
one turns upon a fpir.dle. The oppofite furfaces of the 
two ticnes, which aOt to grind the corn, are not plane or 
flat; but the upper one is hollow, and the under one 
fwells up; each of them being of a conical figure, whofe 
axis indeed is very fliort, in proportion to the diameter of 
its bale ; for the upper one, being fix feet in diameter, is 
hollowed but about one inch at its centre ; and the lower 
one rifes but about three-fourths of an inch. Thefe two 
hiill-ttones cofne nearer and nearer towards their circum¬ 
ference, Tvhereby the corn that falls from the hopper has 
room to infinuate between them as far as two-thirds of the 
radius,which is the place where it begins to be ground, and 
where it makes the greatett reliftance that it is capable of; 
the fpace between the two (tones being in that place about 
two-thirds or three-fourths of the thicknefs of a grain 
of corn. But, as the millers have the liberty of railing or 
finking the upper (tone a little, they can proportion its 
diftance from the lower one, according as they would have 
the flour finer or coarfer. 
In order to cut and grind the corn, both the upper and 
tinder mill-ftones have channels or furrows cut in them, 
proceeding obliquely from tljp centre towards the circum¬ 
ference. And tliefe furrows are each cut perpendicularly 
on one fide, and obliquely on the other, into the (tone: 
which gives each furrow a (harp edge ; and in the two 
(tones, they come, as it were, againft one another, like the 
edges of a pair of fciffars ; and fo cut the corn to make it 
grind the eafier,, when it falls upon the places between the 
furrows. Thefe are cut the fame way in both ltones 
when they lie upon their backs, which makes them run 
crofs-vvays to each other when the upper (tone is inverted 
by turning its furrowed furface towards that of the lower; 
for, if the furrows of both (tones lay the fame way, a 
great deal of the corn would be driven onward in the 
lower furrows, and fo come out from between the (tones 
without being cut. When the furrows become blunt and 
fliallow by wearing, the running (tone mult be taken up, 
and both (tones new dre(fed with a chiifel and hammer. 
But, by this repeated operation, their thicknefl'es, and 
confequently their weight, dimini(h; and it is obferved, 
that, when they come to have but three-quarters or half 
of the thicknefs which they had when new, they produce 
but three-quarters or half the flour which they yielded at 
the beginning. 
The circular motion of the upper mill-ftone brings the 
corn out of the hopper by jerks, and caufes it to recede 
from the centre towards the circumference, where, being 
quite reduced to flour, it is thrown out of the mill, by 
the centrifugal force of the (tone, through a hole provided 
on purpofe. The diameter of common mill-itones, ac¬ 
cording to Dr. Defaguliers, is from five to feven feet, and 
their thicknefs, twelve, fifteen, or eighteen, inches; they 
laft thirty-five or forty years ; and when they have been 
long ufed, fo that their thicknefs is confiderably dimi* 
niflied, they are cut anew, fo give their furface a con¬ 
trary figure to what they had before; fo that the upper 
mill-ftone is made the lower. 
The ufe of mills and mill-ftones, according to Paula- 
ni.as, was nrft fhown by Myla, fon of Meleges, firft king 
of Sparta ; though Pliny attributes the invention of every 
thing belonging to bread and baking to Ceres: Polydore 
Virgil was not able to difcover the author of fo ufeful a 
machine. It is doubted whether or not water-mills were 
known to the Romans, there being no mention made, in 
the Digeft, but of mills turned by flaves and afles. Sal- 
mafius however, and Gothofred, will not allow water¬ 
mills to have been unknown to the ancient Romans, 
although they were not in ordinary ufe. Wind-mills are 
of more modern invention; the firlt model of thefe was 
brought from Alia into Europe in the time of the holy 
wars. For a hiftory of the progreffive improvements in 
corn-mills, fee the article Mill, vol. xv. 
As long as the natural freedom of man continued un¬ 
confined by a multiplicity of laws, every perlon was at 
liberty to build on his own lands and pofteffions whatever 
he thought proper, particularly water and wind mills. 
This freedom was not abridged even by the Roman law. 
But, as it is the duty of rulers to confult what is belt for 
the whole fociety under their protection, princes took 
care that no one (hould make fuch ufe of common ((reams 
as might impede or deftroy their public utility. On this 
account, when water mills began to be numerous, they 
reftrained the liberty of erefting them, and allowed them 
only when after a proper inveltigation they were declared 
to be not detrimental. Water-mills', therefore, were in¬ 
cluded among what were called regalia-, and among thefe 
they are exprefsly reckoned by the emperor Frederic I. 
On fmall Itreams, however, which were not navigable, the 
proprietors of the banks might build mills every-where 
along them. The avarice of land-holders, favoured by 
the injuffice of governments and the weaknefs of the 
people, extended this regalia not only over all ftreams, 
but alfo over the air, and wind-mills. About the end of 
the fourteenth century, the celebrated but long-fince-de- 
ftroyed monaftery of Auguliines, at Windfheim, in the 
province of Overyfl'el, were defirous of erecting a wind¬ 
mill not far from Zwoll; but a neighbouring lord endea¬ 
voured to prevent them, declaring that the wind in that 
diftrift belonged to him. The monks, unwilling to give 
up their point, had recourfe to the bifliop of Utrecht, 
under whofe jurifdiCtion the province had continued fince 
the tenth century. The bifhop, highly incenfed againft 
the pretender who wiftied to ufurp his authority, affirmed, 
that the wind of the whole province belonged to him 
only ; and, in 1391, gave the convent exprels permiffion 
to build a wind-mill wherever they thought proper. In 
the like manner the city of Haerlem obtained leave from 
Albert count palatine of the Rhine to build a wind-mill, 
in the year 1394. 
Another reltraint to which men in power fubjefled the 
weak, in regard to mills, was, that vaifals were obliged to 
grind their corn at their lord’s mill, for which they paid 
a certain value in kind. The oldeft account of fuch ban- 
mills, molcndina bannaria, occurs in the eleventh century. 
Fulbert, bifhop of Chartres, and chancellor of France, in 
a letter to Richard duke of Normandy, complains that 
attempts began to be made to compel the inhabitants of 
a part of that province to grind their corn at a mill fitu- 
ated at the diftance of five leagues. It is not difficult to 
account for the origin of thefe ban-mills. When the 
people were once fubje&ed to the yoke of (lavery, they 
were obliged to fubmit to more and feverer fervitudes, 
which, as monuments of feudal tyranny, have continued 
in fome countries to more enlightened times. De la Mare 
gives an inftance where a lord, in aftran'chifing his (ub- 
jedts, required of them, in remembrance of their former 
fubjedtion, and that he might draw as much from them 
in future as poflible, that they (hould agree to pay a cer- 
1 tain 
