SCIENTIFIC PURSUITS AT HOME
from any sea or lake you choose. Second, two machines for raising weights by means of water, as easily and quickly as is done by mechanical forces. Third, some kinds of sluices, which can be constructed where there is no fall of water, and which will raise boats over hills, sand-banks, etc. Fourth, a machine to discharge by air ten or eleven thousand shots per hour. All these machines are carefully described and calculated algebraically. I had further intended to communicate plans of some kinds of vessels and boats, in which persons may go under water whenever they choose; also a machine for building at pleasure a blast furnace near any still water, where the wheel will nevertheless revolve by means of the fire, which will put the water in motion; likewise some kinds of air-guns that are loaded in a moment, and discharge sixty or seventy shots in succession without any fresh charge. Toward winter perhaps I shall draw and describe these machines. I should like to have the opportunity and the means of setting one or other of them up and getting it to work.
"The day after to-morrow I will travel to the Kinnekulle, to select a spot for a small observa-
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