Splash-Dam.] [Illustration: Fig.21.Logs in Boom.

Glens Falls, New York.] In case such efforts are unavailing, it is necessary to "shoot" the jam with dynamite.

Another device resorted to where the supply of water is insufficient is the _splash-dam_, Fig.20.The object is to make the operator independent of freshets, by accumulating a head of water and then, by lifting the gates, creating an artificial freshet, sufficient to float the timber down stream.
[Illustration: Fig.22.A Sorting Jack.] Thus by one means and another, the logs are driven along until caught by a boom, Fig.

21, which consists of a chain of logs stretched across the river, usually at a mill.

Since the river is a common carrier, the drives of a number of logging companies may float into the mill pond together.