The full detail estimate, from which the following items are extracted, of the cost of alteration was written by Trevithick, jun., in the book and on the page adjoining that containing the account of the former alteration and re-erection of the same engine by Trevithick, sen., in 1775. "A 45-inch cylinder engine, working 20 lbs. to the inch:-- £ _s._ _d._ Boilers, 8 tons at 42_l._ 336 0 0 Iron about ditto, 6 cwt. at 42_l._ 12 12 0 Castings about ditto, 15 cwt. at 42_s._ 18 0 0 Safety-valve and cocks 1 0 0 Wood about bob, 200 ft. at 6_s._ 60 0 0 Cast iron about ditto, 45 cwt. at 25_s._ 56 5 0 Brass about ditto, 60 lbs. at 2_s._ 6 0 0 Piston-rod, 4 in., 14 ft. long, 550 lbs. at 1_s._ 27 10 0 T-piece, 10 cwt. at 25_s._ 12 10 0 Cover, and bottom, and piston, 35 cwt. at 32_s._ 56 0 0 Nozzles, 6 cwt. at 32_s._ 9 12 0 Steam and perpendicular pipe, 10 cwt. at 25_s._ 12 10 0 Receiver, 2 ft. 4 in. long, and bottom, 15 cwt. at 25_s._ 18 15 0 Air-pump, bottom, and case, 10 cwt. at 25_s._ 12 10 0 Plunger, 22 in., 6 ft. long, 12 cwt. at 40_s._ 24 0 0 Force lift 5 0 0 Engineer 66 0 0" The term "single" refers to its open-top cylinder as originally erected by Newcomen, when it was called the Carloose engine, and so it remained after its re-erection in 1775, under the name Dolcoath new engine, alias Bullan Garden; but after the last re-erection in 1799 it had a cylinder-cover, and was called the Shammal 45-inch engine; "working 20 lbs. to the inch" meant the force on each inch of the piston, including vacuum on the one side of 14 lbs. and steam on the other side of 6 lbs. to the inch.