The Italian government may be congratulated on possessing the two fastest and most powerful torpedo boats in the world.  We believe, however, that Messrs. Yarrow are quite confident that, with twin screw triple expansion engines, they can attain a speed of 26 knots an hour, and we have no reason to doubt this.—­The Engineer.

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RESERVOIR DAMS.

[Footnote:  Paper, with slight abbreviation, read by Mr. David Gravell, Assoc.  M. Inst.  C.E., before the Society of Civil and Mechanical Engineers.  The paper brings together in a convenient form the sections and salient facts concerning many dams.  It was illustrated by numerous diagrams, from which our engravings have been prepared.—­The Engineer.]

By David Gravell.

The construction of dams, in some form or other, may probably rank among the very earliest of engineering works.  Works of this character are not infrequently referred to in the accounts of the earliest historians; but it is to be feared that they are not always perfectly trustworthy.  The subscribers to the Mudie of the period had to be considered, and their taste for the marvelous was probably not much inferior to that of our own day.  When, therefore, Herodotus describes the reservoir of Moeris as formed for the control of the river floods of Nile-nourished Egypt, and of another constructed by Nebuchadnezzar at Sippara, of 140 miles in circumference, we must make allowances.  But there is no question as to the existence in the East at the present day, and especially in India and Ceylon, of the remains of what may correctly be termed stupendous works; and the date of the construction of which, as regards India, is in many cases prehistoric.  In Spain also the Moors, whose occupation of the peninsula terminated in the thirteenth century, have left reservoir dams of great magnitude, situated mostly in the south-eastern provinces of Murcia and Alicante, and many of which are still serviceable.

In India and Ceylon the greater number of the ancient dams or bunds are now in ruins, and this can occasion but little surprise, considering the meteorological condition of these countries.  In Ceylon, for instance, the whole rainfall of the year occurs within a period of six to eight weeks, and often amounts to as much as 12 in. in the twenty-four hours, and has been known, comparatively recently, to reach nearly 19 in., the latter an amount only 2 in. or 3 in. less than the average rainfall of Lincolnshire for the whole year.  In London it is only 25 in. and in the wettest district in Great Britain, viz., Cumberland, averages not more than 70 in. per annum.