VARIOUS LNVKNTIONS. 27 



[Rough draft,] 



" .Al II. llOBEIlT Fox, Jim., "CAMBOHNE, February 4t/t, 181:3. 



"Sir, Since I was with you at Falmouth I have made 

 ti trial of boring limestone, and find that the men will bore a 

 hole 14 inch in diameter 1 inch deep in every minute, with a 

 weight of 500 Ibs. on the bit. I had no lump more than 

 12 inches deep ; but to that depth I found that having a flat 

 stem to the bit of the same width as the diameter of the hole, 

 twisted like a screw, completely discharged the powdered lime- 

 stone from the bottom of the hole without the least incon- 

 venience. 



" From the time the two men were employed boring a hole 

 12 inches deep, I am convinced to a certainty that the engine 

 at Hayle will bore as many holes in one day as will be sufficient 

 to split above 100 tons of limestone, and would draw that 

 100 tons of stone from the spot and put them into the ship's 

 hold in one other day. The engine would burn in two days 

 15 bushels of coal, four men would be sufficient to attend on the 

 engine, cleave the stone, and put it into the ship's hold. I 

 think it would not amount to above 9d. per ton, every expense 

 included, but say Is., which I am certain it will not amount to. 

 Perhaps it may not be amiss to withhold the method of exe- 

 cuting this work until the partners have more fully arranged 

 with me the agreement as to what I was to receive for carrying 

 the plan into execution. I do not wish that anyone but your 

 father should be made acquainted with the plan, and have no 

 doubt he will have sufficient confidence in the scheme to adopt 

 it, I shall be glad to hear from you soon, as I intend to go to 

 Padstow in a few days and shall not return under a fortnight. 



" Your humble servant, 



" BD. TREVITHICK. 



" N.B. I this day received a letter from Mr. Gould, request- 

 ing to know what the expense of an engine and apparatus would 

 be tor clearing Falmouth Harbour, which I have sent by the 

 post." 1 



1 Sec letter, 4th February, 1813, vol. i., p. 248. 



