Improved Jury Mast and Shrouds . 217 
eniixg cap, moveable on these additional masts, connects 
them, and the upper parts of these masts are secured 
firmly by trustle trees in the main top. The foot of a 
spare fore top mast passes through a cap made from strong 
plank, morticed into the heads of the two temporary 
masts above mentioned, goes through the main top, and 
rests in the moveable strengthening cap, which connects 
those two masts, and enables the fore top mast to be rais- 
ed to any height which the main top will admit, and be 
then firmly secured by the upper cap, the main top, and 
the strengthening cap below it. The fore top mast being 
thus adjusted, the cross trees and top gallant mast are 
mounted upon it, which completes the whole business. 
Two caps are the only things necessary to be made 
expressly for the purpose, the other articles being usual- 
ly ready on board the ship.^ 
No. 29. 
Letter from Capt» William Bolton, of the Hoyal JSTa- 
vy, on his improved Jury Masts ? and on a Contrivance 
for better securing the Shrouds of Ships, f 
(With a Plate.) 
SIR, 
Finding some doubts were entertained relative to the 
practicability of rigging jury masts, upon the plan I had 
* The references to the Engraving in this communication are the same with 
those that are given at the end of the next paper by the same gentleman j 
they are therefore omitted here. Ed. 
f Nicholson, vol. 25, p. 357. From Trans, of Soc. of Arts, vol. 27, p. 189i 
Some doubts having arisen as to the practicability of rigging Captain William 
Bolton’s improved jury masts, described in vol. 26, page 167, of the Socie- 
ty’s Transactions, (see preceding paper,) he in consequence has sent to the 
Society another model thereof completely rigged, which obviates all difficulty 
therein ; and likewise has added another invention of his contrivance, for the 
better securing the shrouds of rigging; explanatory engravings of both are 
annexed, and the model is preserved in the Society’s Repository. The gold me- 
dal of the Society was voted to Captain Bolton for his naval improvements. 
Vol. i*. e e 
