*Cylindrical.* Having the form of a cylinder. A barrel-like shape or form. *Cycle.* A period; a time during which certain elements operate or act. *Cycle (Two).* An internal combustion engine, in which the gas is drawn in and exploded at each revolution of the crank shaft. *Cycle (Four).* An internal combustion engine, in which the gas is drawn in and exploded at every other revolution of the crank shaft. *Dead Center.* A term to designate the inoperative point of the crank. *Deflected.* Driven away; thrown off. *Depression.* A recess; a sunken part. *Designated.* Named; set forth; pointed out. *Deteriorate.* Depleted; grown worse. *Deviation.* Changed from a certain course. *Diameter.* The direction across a body. *Diagonally.* Any direction which is not across a body at right angles, nor longitudinal. *Diagrammatically.* A drawing which shows the relation and operation of parts, without showing them in the correct mechanical structural forms. *Diagram.* A drawing or sketch which shows the characteristics of a structure in simple lines. *Diagnosis.* An examination which takes into consideration all the elements which make up the condition. *Differential.* Any mechanism which seeks to take care of and utilize the difference of speed or power in the various elements in a machine. *Dioxide of Manganese.* The native state of manganese. *Disengaged.* Separated from; not attached. *Distillation.* The act of abstracting a substance by vaporization, and afterwards returning the vapor to a liquid form by means of a cool temperature. The act of separating the more volatile from the less volatile parts of a substance. *Dissecting.* Taking apart; viewing the separated or different elements. *Distribution.* Spread about; in electricity, the method of directing the current to various parts of the system.