Prosecute.—To follow up until a conclusion is reached.

Pro Rata.—In proportion.

Psychological moment.—The exact time to impress the mind in the best way.

Psychology.—(1) A branch of philosophy. (2) The science of the mind and its operations.

Ramifications.—Subdivisions of a subject or branches of a thing.

Reaction.—A turbine wheel turned by steam forced from it against the air.

Rectify.—(1) To make right whatever is wrong. (2) To make a direct current of an alternating current.

Rectangle.—A four sided plane with right angle corners.

Reject.—To refuse to accept, as to reject a claim in a patent.