Suppose a line of two feet tube laid frorr Boston to New York, it would contain abou 4,000,000 cubic leet of air. Suppose twent] pumps often feet diameter, and ten foot stroki are located at the Boston end, connected wit! the cylinder; these twenty pumps contaii about 15,714 1-7 cubic feet. Suppose thi pumps are worked twenty-strokes in a minute we have removed 314,285 2-7 cubic fee' of air. Suppose the plunger was let in at New York at the commencement of operating th pumps, and the pumps continued to run, fo: fifteen minutes in which same rate 4,714,27! 2-7 feet of air would be removed and the cylinder only containing 4,000,000, the plungei must reach Boston about as soon as this worl coul d be performed so lar as we can see, ant the same result the other way. If the sam number of pumps are worked at the same rate and for the same time, at New York allowing the plunger to be put in at Boston when the pumps are set to work, and all the power used would be applied directly tc moving the plunger and load; the air being removed from before the load no resistance could be had from it, and the power applied to the pumps is directly applied to drawing the plunger. And if the number are not sufficient to perform the work as last as is necessary, more pumps may be added or of a larger calibre, this appears to be good theory, and so far as it has been tried, is good practice.