without incon 

 venience 



J20 w*« rawiinson's colour mill. 



method hitherto adopted of grinding colours on an horizon^ar 

 marble flab, with a fmall pebble muller, requires the body oF 

 the perfon who grinds to bend over ihatllab, and confequently 

 his head; which caufes him conflanlly to inhale the noxious 

 and poifonous volatile parts of the paint, which is not unfre- 

 queptly ground with oil faturatqd with litharge of lead ; and 

 if we may judge from the very unhealthy appearance of thefe 

 men, accuftoraed to much colour-grinding, it (liould feem the 

 bad effeds of this employment require a fpeedy remedy. 

 Machine by "[jrhe machine, of which I now fetid the Society a model, 



ilm'^uch'beTtw^ has not only the advantage of being an effeaual remedy of 

 performed, and this extenlive and fevere evil to recommend it, but it grinds 

 the colour much eaficr, much finer, and much (juicker, than 

 any method hitherto adopted. Having occafion for a con- 

 fiderable quantity of colourrgripding in the profeffion in which 

 ■f. am engaged, and that in the finefl flate potlible, and having 

 made ufe of this machine for feyeral years, and being more 

 and more convinced of its utility^ I thought it my duty to 

 prefent it to the Society of Arts, hoping that it might not be 

 altogether unworthy of their attention. The roller of ihe mar- 

 chine that I ufe is fixteen inches and a half in djameter, and 

 four inches and a half in breadth. The concave muller that 

 jt works againft covers one-third of that roller : it is there- 

 fore evident, that with this machine I have feyenty-two 

 fquare inches pf the concave marble muller in conftanl worlt 

 on the paint, and that | can bring the paint much oftener 

 under this muller in a given fpace of time, than I could by 

 the ufual method with the pebble muller, which is feldom 

 more than four inches in diameter, and confequently has 

 fcarcely fixteep fquare inches at work on the paint, when 

 my concave muller has feventy-two. I do not mean to fay 

 that a roller, the fize of that w-hich I now ufe, is the largeft 

 which might be employed; for truly 1 believe that a roller 

 two feet in diameter, with a concave muller in proportion, 

 would not be hard work for a man; and then the advantage 

 to the public would be flili farther increafed. 



T'his machine will be found equally ufeful for the colours 



It works with 

 five times the 

 furface of the 



muller. 



an j is applicable 

 to water-colour 

 as well as thofe 



to water-colours g^Q^j^ J jj^ water, as for thofe ground in oils; and I doubt not 



in oil, but the great importance of this fimple machine will be very 



foon generally experienced in all manufafclories where colours 

 are ufed. The labour nectllary with this machine, in grind- 



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