* * * *

INFORMATION WANTED.

Mr. Editor,--I have a saw-mill which draws thirty-six square inches of
water, under thirty feet head. I wish to build another below with only
twenty feet head of water. How many square inches aperture will be
required to discharge the same quantity in the same time? If some of
your correspondents will give me an answer, they will much oblige me.
R. C. Navarino, Sept. 7, 1846.

We shall have no occasion to depend on correspondents for the
intelligence above required. Thirty-six inches of aperture under
thirty feet head, will admit the discharge of 660 cubic feet of water
per minute; the velocity of the water being forty-four feet per
second. Under twenty feet head the velocity is only thirty-six feet
per second, and consequently forty-four inches aperture is required to
discharge an equal quantity.

_Rule in Hydraulics_: (never before published.) To ascertain the
velocity of water issuing through an aperture under a given head:
Multiply the head in feet by 62, and the square root of the product
will show the velocity in feet per second.

* * * * *

RAILROAD INTELLIGENCE.

Old Colony Railroad, from Boston to Plymouth, Mass., has for some time
past been in full operation, and is doing a fair business.

The whole amount of the stock of the Michigan Central
Railroad--$2,000,000--has been taken up, and of course the enterprise
will go forward.

On the first day of the opening of the subscription books for the
stock of the New York and Boston Railroad, the people of Middletown
took shares to the amount of $350,000; and they expect to go up to
half a million.

The Cheshire N. H. Railroad is going ahead rapidly, the grading and
bridging on every part of the line being in progress. This road is to
be carried over the Connecticut River at or near Bellows' Falls.

The stock of the Wilton N. H. Branch Railroad is said to be all taken
up.

A General Meeting of the proprietors of the St. Lawrence and Atlantic
Railway was recently held at Montreal. It appears by the report of the
board of directors, that 5,364 shares had been taken up, amounting to
about L1,200,000. All parties appear to be confident that this road
will be constructed and in operation at an early day.

The Little Miami Railroad having been opened to Springfield, is doing
a fair business, and adds important facilities to trade in that
section.

The direct