1. A new radiation integrator is described similar to one previously described by Buxton.

2. Methods of construction are given in detail to facilitate the standardization of future instruments.

3. Instruments of different sensitivities have been constructed by the use of either alcohol or water as the volatile liquid. The alcohol instruments can be used for determining changes in intensity over short periods of time; the water instruments are of most value for determining the mean daily intensity of sunshine.

4. The instruments have been calibrated against absolute measurements with a pyrheliometer. Compared with previous instruments of the same type a very much improved efficiency has been obtained.

5. The value of this type of instrument for work in the field is discussed; its limitations are briefly indicated.

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