302 Proceedings of Philosophical Societies. f April, 



ROYAL ACADEMY OF SCIENCES AT PARIS. 



An Anal If sis of the Labours of the Royal Academy of Sciences 

 during the Year 1818. 



{Continurd from I). 224.) 



Netv Method of laying the Strands of Cordage, proposed by 

 M. Daboul, Master liopemaker for the Merchant Service at 

 Bordeaux. — CommiUee, Messrs. Girard, Molard, Sane, and 

 Dupin, Secretary. 



To lay the strands of a rope is to put together and unite by- 

 twisting, the elements of the rope which they call strands, and 

 which are themselves formed of other srlands twisted together, 

 or of simple threads uniformly twisted. Duhamel-Dumonceau 

 made a number of experimentii in our dock-yards in order to 

 appreciate the different methods in use, which had been disco- 

 vered by frequent trials, and preserved by custom. The only 

 fault that can be found with him is that of having employed 

 clumsy machinery, which did not allow him to attain a sufficient 

 degree of precision. Dynamometers have been constructed 

 some years past, upon the plan of M. Hubert, which serve to 

 determine the strength of hemp. The torsion which they can 

 produce, however, does not go beyond 2000 kilogrammes (one 

 ton) ; it is necessary that they should be made to produce a tor- 

 sion of 100,000 kilogrammes (50 tons), similar to those which 

 have been constructed in England, to try the strength of iron 

 cables and those of hemp. M. Marestier is the first person in 

 France who resolved the problem of twining hemp, and laying 

 strands of an indefinite length in a limited space. M Chanot 

 afterwards resolved the same problem ; and by a remarkable 

 chance, his solution of it was found to be the same with that of 

 M. Marestier in every important part of the mechanism. M, 

 Hubert has been able to comb hemps in a very expeditious and 

 regular manner, and to twine them with a veiy light v.'heel> 

 "without any change of position either of the wheel, or of the 

 workman. Lastly, Col. Lair has just perfected the laying down 

 of cables by equal^cing the strain that is necessary to hinder the 

 strands of the cable from twisting too quick, before the strands 

 themselves have attained the most advantageous twist. M. Du- 

 boul, who has already shown a very remarkable talent in work- 

 manship, now appears as the author of several methods of 

 increasing the strength of cordage. In general, he twines his 

 cordage less, and twists the simple strands more in proportion ; 

 aftervvards, he twists less the first, and still less the second lay- 

 ing down of the strands. The Committee discussed the inconve- 

 niences and advantages of these innovations, and they think 

 that the new proportions given by M. Duboul merit due exami- 

 nation, and that they ought to be tried with a well-made set of 

 comparative experiments. The two machines that M. Duboul 



