An instrument for showing the depth of rain or quantity falling on a given surface at any place. These instruments are variously constructed; the one shown in the engraving on the following page is the invention of Mr. Crossley, and is an elegant application of his patent liquid metre. 1'he principal parts of this machine, which are enclosed in a small box a a and b, are, a small tin vessel or tumbler e f, which is divided into two equal parts by a vertical partition, where it is supported by pivots on the upright stem l. The pivots are placed below the centre of gravity of the tumbler, so that when it is tilted (as represented in the engraving), it will remain in that position till the upper half receives such a quantity of water as will overbalance it, when the end c will be depressed by the weight of the water, and emptied; the end f will, in consequence, be elevated and brought under the spout to receive the water until it becomes sufficiently loaded to preponderate, when it will again take the position in the figure.

Attached to this tumbler is a forked projection, that at every change of position, acts on a lever at f f, and thus communicates motion to a train of wheels, which, by the index and the dial face i, is made to register the number of times the divisions of the tumbler have been filled. The rain is received and conveyed into the tumbler by the hopper-shaped vessel c c, the mouth of which must be made of an area, having such a relation to the other parts that the index will point out the number of inches of rain falling on that extent of surface; or, in other words, how deep the water would have become had it remained on the surface of the earth during a single shower, a day, a month, or even a year, if required, and this, too, without any attention or care being bestowed upon it - for the apparatus is so simple in construction, that it is not subject to derangement of its parts; and as it registers during the falling of the shower, it requires no estimation to be made of the quantity of water evaporated between the falling of the rain and the time of observation.