gja Description of a Capsiait. 



messenger must suffer in the operation, while pressed so 

 hard against the capstan, (as it must be by the weight of the 

 anchor and strain of the men,) could not but cause a very 

 great wear and injury to the messenger, or other cable 

 wound round the capstan ; and that this wear must ofcca- 

 sion an expense of no small amount, must be manifest on 

 considering the large sums which the smallest cables used 

 for this purpose cost. 



The next method applied to prevent surging, was that for 

 which Mr. Plucknet obtained a patent, the specification of 

 which may be seen in the Repertory of Arts, No. 46. In 

 this way a number of upright puppets or lifters, placed 

 round the capstan, were made to rise in succession, as the 

 capstan turned round by a circular inclined plane placed 

 beneath them, over which their lower extremities moved on 

 friction wheels; and these puppets, as they rose, forced 

 upwards the coils of the messenger on the barrel of the cap- 

 stan. This was a superior method to the first, as the ope- 

 ration of forcing upwards the coils was performed more 

 cradually by it ; but still the wear of the messenger from the 

 lateral friction in rising against the whelps of the capstan re- 

 mains undiminished. 



The third method used for the same purpose was that 

 proposed by captain Hamilton. It consisted in giving the 

 capstan a conical shape, with an angle so obtuse, that the 

 strain of the messenger forced the coils to ascend along the 

 sloped sides of the barrel. The roller first mentioned was 

 sometimes used with this capstan, of which a full account 

 is inserted in the Kepertory of Arts, vol. ii. The lateral 

 friction, and wear of the messenger against the whelps of 

 the capstan, is equally great in this method as in the others ; 

 and it, besides, has the inconvenit-nce of causing the coils 

 to become loose as they ascend ; for as the upper part of the 

 barrel is near a third less in diameter than the lower part, 

 the round of the messenger that tightly embraced the lower 

 part, must exceed the circumference of the upper extremity 

 in the same proportion. 



In the method of preventing the necessity of surging, 

 which the model I have had the honour of laying before 



the 



