Mr. Ttawlinson’s Colour Mill. 
457 
head ; which causes him constantly to inhale the noxious 
and poisonous volatile parts of the painty which is not 
unfrequently ground with oil saturated with litharge of 
lead ; and if we may judge from the very unhealthy ap- 
pearance of these men, accustomed to much colour grind- 
ing, it should seem the bad effects of this employment re- 
quire a speedy remedy. 
The machine, of which T now send the Society a mo 
del, has not only the advantage of being an effectual re- 
medy of this extensive and severe evil to recommend it, 
hut it grinds the colour much easier, much finer, and 
much quicker, than any method hitherto adopted. Hav- 
ing occasion for a considerable quantity of colour-grind- 
ing in the profession in which I am engaged, and that in 
the finest state possible, and having made use of this ma- 
chine for several years, and being more and more con- 
vinced of its utility, I thought it my duty to present it to 
the Society of Arts, hoping that it might not be altoge- 
ther unworthy of their attention. The roller of the ma- 
chine that I use is sixteen inches and a half in diameter, 
and four inches and a half in breadth. The concave mill- 
ler that it works against covers one third of that roller : it 
is therefore evident, that with this machine I have 
seventy-two square inches of the concave marble mu Her 
in constant work on the paint, and that I can bring the 
paint much oftener under this muller in a given space of 
time, than I could by the usual method w ith the pebble 
muller, which is seldom more than four inches in diame- 
ter, and consequently has scarcely sixteen square inches 
at work on the paint, when my concave muller has 
seventy-two. I do not mean to say that a roller, the size 
of that which I now use, is the largest which might be em- 
ployed ; for truly I believe that a roller two feet in dia- 
meter, with a concave muller in proportion, would not be 
Yol. ii. 3 L 
