We intend, as usual, to devote a small portion of the new volume otthe Scientific American to short advertisements. We are particular, and shall exercise unusual vigilance in admitting them—no quack medicines, or speculations of doubtful character, can be advertized at any price whatever. Wants of in- ' ventors, engineers, and mechanics, sales of ma-J chinery, manufacturing establishments, &c. will be admitted at the rate of 18 cents per line for each insertion,—owing to change in the kind of tyne which will be used, the same quantity of matter will cost no more than at present rates. We shall also require advertisements to be as brief as possible or they will be refused. No advertisements will be received which do not correspond with the general character of the subjects treated in the paper—no attention will be paid to any other