The screw-propellers and paddle-wheels are multiplications from the former era. The variations from the common propeller and paddle-wheel, in the miscellaneous devices, are all under _reductions of merit_. All the bow-propulsions, and all the variations from the _Viele_, _Sternburg_ and _Ruggles_ of the former, and the _Byron_, _Baxter_ and _Newman_ of the present era, are inferior, whether viewed practically or scientifically. Hence, steam has received no mechanical advancements since 1858; and the efforts of 1872 are as positive and determinate failures as those of 1862. THE TRIALS OF STEAM IN 1872 LESS ECONOMICAL THAN IN 1858 TO 1862. It should be observed that the first trials of steam in 1858 were made during a season of low water, and when the Canal Board had limited the loading of boats to four and three-fourths feet draught of water, which, later in the season, was increased to five feet, and in subsequent years to six feet, as continued to the present time. Among the most successful trials of the first era of steam on the canals, may be mentioned the _H. K. Viele_, _P. L. Sternburg_, and _S. B. Ruggles_. Each could carry three-fourths cargo and tow a full cargo, and each exceed the speed of horse-boats. Among the most successful trials of the present era may be mentioned the _Port Byron_, _Baxter_, and _Newman_. Each can carry five-sixths of a common cargo, and exceed the speed of horses. In the early era of steam, _the prominent policy_ was to combine towage with carrying capacity by the steamer, for economical expedition. In the present era, it has been to make the carrying capacity of the steamer, in itself, economical and expeditious. This latter policy has arisen under the Appropriation Act of April, 1871, which limits the minimum cargo to two hundred tons, and the minimum average speed of three miles per hour. But these limitations must cover a superior economy of freight transportation to that by the former trials with steam. Else, they are worthless; else, they are failures, as in 1862, and their general introduction impracticable. As in the steamers _Byron_, _Baxter_ and _Newman_, _there is nothing mechanically new_, in variation from the _Viele_, _Sternburg_ and _Ruggles_--these trios being _respectively mechanical counterparts of each other_; the paddle-wheels of the _Byron_ and _Viele_, the twin-propellers of the _Baxter_ and _Sternburg_, and the common propellers of the _Newman_ and _Ruggles_, being respectively identical--the economical features are easily considered. The first trio can carry 200 tons at good speed; the second can carry 180 tons, and tow 240 tons; total, 420 tons, at good speed. To the first trio, two boats of each class must be altered; two sets of machinery must be furnished; two corps of engineers maintained, and coal for two round trips must be supplied, with incidental expenses to two steamers, to move 400 tons of freight.