134 COALING WARSHIPS FROM COI^UERS IN HARBOR. 



COALING WITH BAGS. 



The author believes that coaHng with bags will gradually give way 

 to coaling in bulk and a great saving in the cost of bags will then accrue to 

 the Navy. In coaling with bags it takes two men to hold the bag while 

 a third man shovels coal into it. Bags soon wear out and, even when they 

 are stowed away, are liable to mildew and rot. After the coaling is finished 

 the bags are usually washed, dried and stowed away. 



BAG-PILLING HOPPERS. 



In case it becomes desirable for any reason to coal with bags it is 

 suggested that these colliers be provided with hoppers to be filled with a 

 clamshell bucket, these hoppers to be constructed so that the coal may 

 spout directly into bags. Thus one man could fill bags from the hopper as 

 rapidly as seven can working in the hold shovelling by hand. This is the 

 result attained by bag-filling hopper barges in use by the British Admiralty. 



MARINE TRANSFER WINCHES. 



The introduction on board ship of machinery to operate a clamshell 

 bucket was new before these ships were built and no ship's winch had ever 

 been constructed for this purpose. Deck space is valuable and limited. 

 It is also important to save weight of machinery. The winches shown in 

 Plates 37 and 44, occupy a space of only 7 feet 8 inches by 5 feet lo^ inches. 

 They weigh 9,400 pounds each. These winches have only 8j-inch by lo-inch 

 double cylinders, yet they have proven to be capable of handling one gross 

 ton of coal with perfect ease and ample factor of safety. In shore towers 

 operating clamshell buckets, two lo-inch by 12-inch cylinders are the 

 smallest used for this size of bucket. Drums driven by wood-and-iron 

 friction clutches are employed on shore towers very extensively and with a 

 fair degree of success, but on shore towers there is ample space for winches 

 having friction clutches of large diameter. Kven 40-inch, 50-inch and 60- 

 inch frictions are employed in some instances. Targe friction surfaces are 

 necessary (when wood and iron are used) to dissipate the heat developed by 

 tlie friction drums repeatedly thrown in and out of engagement. The deck 

 space available on these five colliers limits the diameter of the friction clutches 

 to something like 24 inches, and wood-and-iron or leather-and-iron frictions 

 become impracticable. The winches referred to and illustrated herein have 

 flat metallic frictions provided with air-cooling passages and even these 

 get extremely hot in the course of a run of a single hour, but never hot 

 enough to affect the operation. 



