870 



ANNUAL REGISTER, 1805. 



from litne-stone. Chalk-lime at- 

 tracts moisture; and communicating 

 it to any timber which it touches, 

 occasions its decay. Sea-sand is 

 also prejudicial, if made into mor- 

 tar, from asimilar quality of attract- 

 ing moisture from the atmosphere : 

 this may in some degree be correct- 

 ed by washing the sand well in fresh 

 water, where good sand cannot be 

 procured. 



Good mortar, where any is re- 

 quired to be in contact with timber, 

 may be made from a mixture of 

 stone-lime fresh burnt, and river- 

 sand, to which a very small quantity 

 of common brown or yt'How iron 

 ochre, should be added, and well 

 incorporated therewith. 



Method of' -siispeiuUng Sliips instead of 

 li/ihig t/icm, for tlit Purpose tif 

 clearing t hem from ,t/ieir B/oelm ; 

 by Mr. Robert Scppiitgs, of Chat- 

 ham Yard. 



The following is a description of 

 an invention, by Mr. Robert Scp- 

 pings, late maslt^r ship-wright assis- 

 tant in his majesty's yard at Ply- 

 mouth, (now master-shipwright of 

 his majesty's yard at Cliatham,) for 

 suspending, instead of lifting, ships, 

 for the purpose of clearing ihem 

 from their blocks; by which a very 

 great saving will accrue to the pub- 

 lic ; and also two-thiids of the time 

 formerly used in this operation. — 

 From the saving of time another 

 very important advantage will be 

 derived, that of enabling large ships 

 to be docked, suspended, and un- 

 docked, the same springtides. — 

 Without enumerating the inconve- 

 nicncies arising, and perhaps inju- 

 ries which ships are liable to sustain, 

 rom tbe foiincr practice »f lifting 



them, and which arc removed by tti« 

 present plan ; that which relates to> 

 manual labour deserves particular 

 attention ; twenty men being sufli- 

 cient ii> suspend a first rate, whereas 

 it would require upwards of five 

 hundred to lift her. The situation 

 which Mr. Seppings held in Ply- 

 mouth yard, attached to him, in a 

 great degree, the shoring and lifting 

 of ships, as well as the other practi- 

 cal part of the profession of a ship- 

 wright. Here he had an opportu- 

 nity of observing, and indeed it was 

 a subject of general regret, how 

 much time, ex pence, and labour^ 

 were required in- liftiivg a ship, par- 

 ticularly ships of the line. This in- 

 duced him to consider whether soma 

 contrivance could not be adopted 

 to obviate these evils. And it oc- 

 curred to him, that if he could sO' 

 construct the blocks on which the 

 ship rests, that the weight of the 

 ship might be applied to assist in the 

 operation, he should accomplish this 

 very desirable end. In September, 

 1800, the shoring and lifting the San 

 Josef, a large Spanish first-rate, 

 then in dock at Plymouth, was 

 conunitted to his directions; to per- 

 form which, the assistance of the 

 principal part of the artificers of 

 tile yard was requisite. In conduct- 

 ing this business, the plan, which 

 will be hereafter described, occur- 

 red to his mind ; and from that 

 time, he, by various experiments, 

 proved his theory to be correct: 

 the blocks constructed by him, upon 

 which the ship rests, being so con- 

 trived, that the facility in removing 

 them is proportionate to the quan- 

 tity of pressure; and this circum- 

 stance is always absolutely under 

 command, by increasing or dimi- 

 nishing the angle of three wedges, 

 which constitute one of the blocks ; 



tw» 



