Equatorial oe the Lick Observatory In the February, 1919, number of these Publications an account was given of an investigation of the color curve of the objective of the 12-inch equatorial of the Lick Observatory. In pursuance of the plan mentioned there, we took further measures on the nights of July 16th and 17th, to obtain a more accurate determination of the temperature equation. The method of observing was the same as that described in-the previous paper, and the position of the slit with

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... respect to the base plate was measured as before. Six complete sets of measures by the Foucault method were taken, three by each observer; the mean temperature was + 25°.o C. The resulting "high temperature" color curve is parallel to those for lower temperatures, with a constant difference of 1.67 mm. between this and the curve for 4°.6 C. Thus the temperature equation, as determined from a range of 2i°.4 is R = R 0 + 0.08 mm. (t -9°.i), which is identical with the equation obtained before from a range of 9 0 .