than anthracite is used on those waters, and with such advantage that the rates of freights and passage are essentially reduced, while the profits of running are such as to induce the building of larger and larger vessels all with a view to that species of fuel.
As to the question of the relative value of coal, compared with dry beach, ash and cotton wood, I am not aware that any direct experiments on the latter kinds of wood, have as yet furnished the data for computing that relation. You may have observed that in my report on coals, I have stated that the subject is yet unexhausted, and particularly that the coals of the West and South-west were but very imperfectly represented in the series of samples sent for trial in 1843. Mr Bull, who made experiments on the woods some twenty-five years ago, also experimented on certain coals, and obtained comparative results between weights of coal and cords of wood. But the western coals, those of Illinois, Indiana and Kentucky, were not, I think, then brought into notice, and I am under the impression that cotton wood was not among the kinds submitted to trial by him. One object I had in view in requesting the Government to continue the experiments on coal was to perform at the West a second series of trials on the coals and woods found on the Western Lakes and rivers. From all that I do know of the Western coals, and from all that I have learned from others, cf the wood of the Western country, I do not entertain a doubt as to the great economy of using coal wherever it can be had at a moderate price.
It is very certain that with prices such as have hitherto ruled on the Ohio and its branches, one could hardly suppose any other fuel than coal would be used, if the trips were confined to the coal region, or to a moderate distance beyond it.
The grates for using coal will in general be of less depth than those for the use of wood; the bars will be from ^ to f of an inch apart. But for different coals different dimensions of grate will be required. I suppose one difficulty experienced on the Western boats will arise from the attempt to burn too much coal at a time on the bars, by which means the iron will become over-heated and fused, and if the clinken be also heated to the fusing point, the sulphur will attack the iron and run into compact masses with it, preventing the clearing of the fire. A thin stratum of coal on a grate raised to within a few inches of the bottom of the boiler will be probably found the most ad-