shall now keep our promise by making known a work that Mr. Pictet has
just published in the _Archives Physiques et Naturelles_, of Geneva,
in which he gives the first results of his labors, and which we shall
analyze rapidly, neglecting in doing so the somewhat dry mathematical
part of the article.

For a given tonnage and identical tractive stresses, the greater or less
sharpness of the fore and aft part of the keel allows boats to attain
different speeds, the sharper lines corresponding to the highest speeds,
but, in practice, considerably diminishing the weight of freight capable
of being carried by the boat.

[Illustration: FIG. 1. PICTET'S HIGH SPEED BOAT.

A. Lateral View. B. Plan. C. Section of the boiler room. D. Section of
the cabin.]

Mr. Pictet proposed the problem to himself in a different manner, and as
follows:

Determine by analysis, and verify experimentally, what form of keel will
allow of the quickest and most economical carriage of a given weight of
merchandise on water.

We know that for a given transverse or midship section, the tractive
stress necessary for the progression of the ship is proportional to the
_square_ of the velocity; and the motive power, as a consequence, to the
_cube_ of such velocity.

[Illustration: Fig. 2.--Diagram of tractive stresses at different