Improved Crane and Flexible Chains. 257 



barrel for the chain, works between them. The piece at the 

 top contains in the middle a dove-tailed mortise, into which 

 a stock for the gib is fixed ; for greater security, an iron 

 bolt goes through the whole ; the stock projects two feet 

 from the mortise, and a plank eighteen inches deep, and 

 four thick, is bolted to each side of it to form the gib, the 

 interstice between the planks forming a birth for the top 

 block to slide in. The diagonal stay is of the same dimen- 

 sions, formed in a similar manner, and connected to the per- 

 pendicular, by being let into the lower mortise piece. 



In this mode of construction scarcely any part of the tim- 

 ber is cut away ; and the strength of the materials, so far 

 from being diminished, is augmented by the cast-iron mor- 

 tise pieces, the gib is brought much closer to the upper gud- 

 geon, and the centre lines of the perpendicular and the dia- 

 gonal stay crossing each other at the top of the lower one, 

 places the whole strain as near as possible in a line with the 

 gudgeons. The business of the perpendicular becomes in. 

 consequence little more than that of a mere prop, and con- 

 sequently requires no greater strength of materials than the 

 diagonal stay. 



The top block is made of cast iron, and has a groove 

 three inches deep on each side, for the purpose of embra- 

 cing the planks which form the gib. 



To prevent the inconvenience of the dirt of the floor get- 

 ting into the brass of the lower gudgeon, and thereby ob- 

 structing the revolution of the crane, those parts are reverse 

 to the common way, the gudgeon being fixed in the floor, 

 and the socket part which embraces it is cast in the bottom 

 of the mortise-piece, as is also a channel to convey oil to the 

 gudgeon. I am, Sir, 



Your most humble servant, 



Gilbert Gilpin. 



Old Park Iron-works, near Shifnal, 

 April 16th, 1804. 



Reference to Mr. Gilbert Gilpin's Crane, PI. VT. 



Fig. 1, 2, 3, 4. 

 Fig. 1 . represents the crane with all its parts complete, 

 ready for work. 



Vol. 25. No. 99. Aug. 1806. R AB, 



