296 British Association for the Advancement of Science. 
one third of the breaking weight. Mr. Fairburn said, always—and 
afterwards replied to a question from Mr. Guest, that the Scotch hot 
blast iron showed a greater comparative strength as compared with 
cold blast, but that they had made no experiments on South Welsh 
iron. There was a perceptible permanent set from 280 lbs., the 
experiments being of from five to ten minutes in duration, and it be- 
ing possible to judge the deflection to the one thousandth part of an 
inch.—Mr. Webster said it had been found that the first set was 
owing to the breaking of the first crust, and that beyond the first 
permanent set up to the elastic limit, the deflexion increases exactly 
as the weight. Some further conversation ensued, in which Mr. 
Smith and others took part, when Mr. Guest suggested the propriety 
of farther continuing these researches, to which the President agreed, 
and suggested a recommendation to this effect from the committee 
of the section to the general committee. Thanks were then voted 
to Mr. Fairburn for the zeal and skill with which he had prosecuted 
these researches for the Association. 
Rail Roads and Canals in the United States—Prof. Henry, of 
New Jersey College, Princeton, U. S. then addressed the section, 
and said, he had been requested to present to the Association a map 
of the United States, in which were marked the railways and canals 
completed and in progress. ‘They had been fully described in some 
French works lately published, and in the American Almanac. 
After enumerating several geographical facts well known to our 
readers, as to the three natural divisions of America, the Atlantic 
slope, the middle basin of the Mississippi, and the Pacific slope, &c. 
he mentioned that there were now one thousand five hundred miles 
of railway in operation in the United States, and two thousand miles 
of canals ; and that three thousand miles of railway were in progress, 
which had been in a great degree interrupted, owing to the late com- 
mercial convulsions.—In answer to a question put by Mr. De Butts, 
he stated, that, on the Hudson, there being very little current, one 
hundred and fifty miles were frequently accomplished by the steam- 
boats in nine hours.—Dr. Lardner much doubted, whether a speed 
of fifteen miles an hour could be generally attainable-—Mr. Webster 
stated, that Mr. Blunt, an American engineer, had, in a pamphlet 
which he quoted, declared, that the American boats had aceomplish- 
ed seventy four miles in five hours, and that the distance from New 
York to Albany, one hundred and fifty miles, was performed in ten 
hours by boats built principally with a view to speed. 
(To be continued in the next No.) 
