The change-of-state crystal oven

A description is given of a new high precision crystal oven which depends for its action upon the natural stability of the melting point of a pure crystalline material and upon the thermal ballasting which the property of latent heat of fusion provides. The necessity for complicated controlling circuitry is avoided, the power to the oven being controlled simply by means of a micro-switch. The underlying principles are explained, and constructional details given with a brief account of development problems and their solution. A summary of the results obtained is given: a change of 10 deg C in ambient temperature causes a frequency shift of 2.8 parts in 108