Setting a unit of measurement for solar radiation (the 'actine'); proposes to 'take for a unit of solar heat that which if all employed in heating a cubic inch of water exposing a horizontal surface of one square inch, to a vertical Sun during one minute would produce a dilation of one thousandth part of its volume.'

Definition at the Observatory last night was abominable; therefore no comparisons can be made between the stations. Much obliged for the details of the actinometer. Will call on JH later.

Testing whether an actinometer with a glass back is more accurate than one without.

From a newspaper received today sees that John Pond is dead and buried. Affair of James South and Edward Troughton and William Simms is as before. Sends the observations of the 21st; rain was not good for astronomical observations. Comments on these readings.

Thinks Monday 2 Jan. a suitable day for taking down the Circle. Has engaged J. K. Gibbs the carpenter for the coming quarter. No official notice has been taken of his Colonial Measure of Reference.