30 ANM'AI, OF SCIENTIFIC DISCOVERY. 



DUTY OF STEAMSHIPS. 



A committee of the British Association for the Advancement of Science 

 of which Mr. Fairbuirn was chairman appointed to consider the above 

 subject, at the meeting for 1858, recommends that all the owners of steam- 

 ships adopt means to register their efficiency. The rule which they lay 

 down for testing vessels, is, to multiply the cube of the speed by the square 

 root of the cube of the displacement, and divide the product by the con- 

 sumption of fuel per hour in hundred-weights. Thus, if a steamer, A, per- 

 formed a voyage of 7200 miles in 652 hours, on an average speed of 11 '04 

 knots, and the consumption of coal was 47 cwts. per hour, and the mean 

 displacement 2934 tons, the coefficient of dynamic duty indicating the 

 merits of the performance would be 



(11-04)3 X (2934}f -|- 47 = 5870. 



Suppose another steamer, B, having a displacement of 840 tons, average 

 speed 12'78 knots per hour, consumption of coal 50'3 cwts., then the coeffi- 

 cient of duty is 



(12-78)3 X (840)| -f- 50-3 = 3693. 



In the first case, A performs as much work with 1 cwt. of coal as B with 

 1 l-16th cwts. It is only by computing the amount of coal used, with the dis- 

 placement of the vessel and its speed, that we can arrive at any data regard- 

 ing the efficiency of steamers. The cause of superiority in one vessel may 

 be in its form, or the machinery; but, whatever it may be, there is no possi- 

 bility of finding this out, unless the displacement, speed, and coal consumed, 

 are known. A series of statistics of the performances of steamers under 

 such a test, would lead to a close investigation as to the causes of superiority 

 in one over another, and the result would be a general adoption of those 

 improvements by which the advantages were secured. At present there are 

 steamers which do the same duty as others with one-fourth less fuel ; but no 

 person can really tell whether this is owing to their models, or machinery, 

 or some other cause. 



WIAPtD'S PATENT ICE-BOAT. 



This is a steamboat on runners, intended to navigate the Northern rivers 

 and lakes in winter, when closed with ice of sufficient thickress to support 

 its weight Avith safety. It is constructed with a water-tight hull, so that in 

 case it should break through the ice, or come to open places in the river, it 

 will float on the water without harm to itself, cargo, or passengers. We 

 copy the following from a pamphlet on the subject, written by the inventor: 



"It is safe to say that not less than twenty-two thousand miles of ice-road 

 nro embraced within the limits *f the United States and Territories. In 

 addition to this immense field, there are still others in the British Provinces 

 and the north of Europe. By means of the ice-boat, remote regions of our 

 country, shut out in winter, will be brought into constant connection with the 

 cities of Chicago, St. LouK Washington, New York, and Boston. 



"In the winter of 1858-9, 1 constructed, at Prairie-du-Chien, my first ice- 

 boat. It was my intention to have it completed in time to make a trial of 

 speed upon the ice of the Mississippi River, between Prairie-du-Chien and 

 St. Paul, in the spring of 1859; but in this I was disappointed, by the reason 

 of the breaking up of the ice in that river a month earlier than usual. The 



