A rack for use in precipitation tests.

It consists of a block of wood 93 in. by 3 in. by 2 in. into which have been drilled forty-eight holes of j in. diameter in four rows of twelve. The top of the wooden rack is covered by a thin sheet of white plastic, drilled with holes of a similar size and position to those on the wooden block. Fixation on to the wood is secured by glue and six -brass screws. The plastic top has the advantage that it can be written on with a grease pencil without being heated, and it is easily cleaned by one or two rubs of a duster. The noise of rattling tubes when the shaking takes place is, for practical purposes, eliminated, A second advantage of this rackis that its shape is not distorted after use. Metal racks suffer from this defect.