M A R 
given to this frame by the rod I, communicating with the 
crank O K, which is turned by water or fleam. This 
frame, being put in motion, gives motion to the faw- 
frames LL, MM, and to the polifhing arms N, P, Q, which 
■work on the pivot P, and are pufhed backwards and for¬ 
wards by the connecting iron rods n n. The faws are 
iron plates fhaped like a common faw, and faftened 
into oblong rings by means of pins. Thefe rings are put 
upon the crofs bars EE, b b and the faws are ftretched 
tight by the fcrews s ss and c. R R, S S, are four upright 
ports conftituting a frame, in which are placed the blocks 
of marble to be fawn into (labs, which are at the fame 
time to guide the frame of the faw. At each end of this 
frame there area number of upright fquare bars of iron it, 
between which the faws pafs, which bars aft as conductors. 
The ports R R can be removed to a greater diftance, fo 
as to make the frame longer for receiving different-fized 
blocks. The part T, to which the faw is attached on the 
moveable frame. Aides upon the upright poft A C. It is 
fufpended by a rope, which goes over a pulley c, and is 
counterbalanced by the weight W. By this means the 
faw may be made to prefs upon its work with any degree 
of force. It will be evident that the moveable frame, 
from"its pendulous motion, does not move in a rtraight 
line, but a curve. The Aiding part T, therefore, ferves 
to induce a rectilineal motion of the faw. The upright 
bars of iron, it and c, are of a fize equal to or lefs than 
the thinned Aabs, fo that the faws may be placed at dif¬ 
ferent diftances, according to the thicknefs of the Aabs. 
In order to alter the faws for this purpofe, nothing more 
is neceffary than to loofen the fcrews s s, and Ihift the 
oblong rings which contain the faws : (thefe are fhown 
feparately at fig. 3.) 
The Aabs of marble to be polirtied are laid upon the 
carriage k, fo as to correfpond with the rubber Q, which 
partes over it in the direction of its length. In order to 
extend the rubber to the other parts of the Aab, the car¬ 
riage, h, has a lateral motion, by means of four grooved 
wheels running upon the iron guiders let into the beams 
8 S' The endlefs fcrew e, in the main Aiaft, turns the 
wheel r. This gives motion to the lever w , fig. 2, by 
means of the crank q. The lever communicates with the 
crank k, and turns the wheel l, more or lefs of a revolu¬ 
tion, according to the length of this crank, which can be 
altered at pleafure by Aiitting the temporary pin f. By this 
latter motion the wheel k works the ratch v , and gives the 
lateral motion to the carriage. By this means the whole of 
the furface is expofed to the aCtion of the rubber. Round 
articles of fpar, gypfum, and marble, are turned in the 
lathe with pointed inftruments of hardened fteel. The 
pieces to be turned are attached to a wooden chock by 
means of cement. The gypfum is very foft, and turns 
with great facility. The fluor fpar and marble require 
the_ tool to be very hard, while the part to be turned re¬ 
quires a conftant fupply of water, which drops from a 
vert'd above. After the articles are turned into the given 
ihape, they are drefled with fand and emery, and after¬ 
wards polirtied with tripoli and putty. 
Small fpecimens for collections of marbles are generally 
olifhed upon a lap, which runs in a lathe. Thefe laps, 
owever, ought to run with the axis perpendicular to the 
horizon, the face of the lap being truly flat and horizon¬ 
tal. The lap ufed for the firft procefs fliould be of iron; 
the. fecond of an alloy of lead and tin ; and the third, 
which is for polifhing, fliould be of iron with pitch. By 
means of fome auxilliary machinery, a number of pieces 
might be polifhed in this way at once, which would fave 
much manual labour. Small pieces of marble may alfo be 
polifhed on the large machine, by cementing them with 
plafter on the furface of a large flab. By being placed 
on the fame level, the large rubber fweeps them all at 
once. 
The marble-mill in the neighbourhood of Kilkenny, in 
*re.and,. and which was invented by alderman Collis,. 
M O R. 351 
grandfather of the prefent proprietor, is remarkble for the 
fimplicity of its ftrudure, and for the powers it exerts. 
One wheel, ten feet diameter, with twelve floats or ladles,- 
gives motion, by a crank at one end of its axis, to a frame 
containing twelve faws, which do the work of about 
twenty men. By a crank at the other end, it moves a 
frame of five polifhers, which do the work of about ten 
men. At this end the prefent Mr. Collis has fitted a frame 
beneath the polifhers, with eight faws, to the motion of 
which he has found the power of the machine fully equal. 
This mill may be fairly faid to do the conftant work of 
forty-two men daily. The faws are made of foft iron, 
and lalt about a week ; they are conftantly fupplied with 
water and fand ; the latter is taken out of the bed of the 
Nore, and waflied till nothing remain but very fine and 
pure filiceous particles. A faw cuts ten inches in a day, 
and twelve when the water is ftrong ; it would require 
two men to do the fame with a hand-law. The marble 
taken from the mill is firft polirtied with cove-ftonc, that is, 
a brown fand-ltone imported from Chefter, and which 
takes its name from being ufed in chimney-coves. It 
is afterwards polirtied by a hone-Jlone, which is a piece of 
fmooth nodule of the argillaceous iron ore, found in the 
hills between Kilkenny and Frefhford. It receives the 
laft polifh in the mill with rags and putty. By means of 
this mill, the marble is fo ealily worked as to be fold at a- 
very moderate price, 
A great improvement in cutting marble and other 
ftones, but particularly columns, by machinery, was in¬ 
vented in Ireland by the late fir George Wright, barf, 
who procured a patent for it. By this .a number of hol¬ 
low columns can be cut from a folid block, each decreas¬ 
ing in fize, fo that nothing of the (tone is loft, except 
what is converted into dull by the faw. 
The colouring of marbles is a nice art; and, in order 
to lucceed in it, the pieces of marble, on which the ex¬ 
periments are tried, mult be well polirtied, and clear from' 
the lealt (pot or vein. The harder the marble is, the 
better it will bear the heat neceffary in the operation ; 
therefore alabarter, and the common foft white marble, 
are very improper to perform thefe operations upon. 
Heat is always neceffary for the opening of the pores 
of the marble, fo as to render it fit to receive the colours j... 
but the marble mult never be made red-hot, for then the 
texture of the marble itfelf is injured, and the colours are 
burnt, and lofe their beauty. Too linall a degree of heat 
is as bad as too great; for, in this cafe, though the mar¬ 
ble receives the colour, it will not be fixed in it, nor 
ftrike deep enough. Some colours will ftrike, even cold 
but they are never fo well funk in as when a juft degree 
of heat is ufed. The proper degree is that which, with¬ 
out making the marble red, will make the liquor boil 
upon its furface. The menftruums ufed to ftrike in its 
colours mull be varied according to the nature of the co¬ 
lour to be ufed. A lixivium made with horfe’s or dog’s 
urine, with four parts quick-lime, and one part pot-alhes, 
is excellent for fome colours ; common ley of wood-afhes 
does very well for others; for fome, fpirit of wine is belt; 
and finally, for others, oily liquors, or common white 
wine. 
The colours which have been found to fucceed belt 
with the peculiar menftruums are thefe:. Itone-blue difi- 
folved in fix times the quantity of fpirit of wine, or of 
the urinous lixivium ; and that colour which the paint¬ 
ers call litmus, diffolved in common ley of wood-afhes. 
An extrafl of faffron, and that colour made of buck¬ 
thorn berries, and called by the painters fap-green, both 
fucceed well diffolved in urine and quick-lime, and to¬ 
lerably well in fpirit of wine. Vermilion, and a fine 
powder of cochineal, fucceed alfo very well in the fame 
liquors. Dragon’s blood fucceeds very well in ipirit of 
wine, as does alfo a tinfture of logwood in the lame fpi-- 
rit. Alkanet-root gives a fine colour, but the only men- 
ftuum to be ufed for this is oil of turpentine5 for neither. 
3, ' fpirit; 
