Thanks TM for restoring JH's micrometer.

Believes that JH and TM can compile a better comet catalog together than they could separately.

Notes a discrepancy in TM's latest observations and those of Thomas Brisbane.

Congratulates TM on the birth of his son, George.

A note along with a request from Niccolo Cacciatore for some observations that JH says he cannot make.

Inquires about a star not found in TM's list of comet stars. Believes that their comet collaboration is going well.

Sends formulae for dealing with the apparent differences, in viewing the comet and compared star, due to the effects of parallax and refraction.

Discusses their table of comet stars.

Much obliged for F. W. Bessel's zone. Thinks his own extra meridian observations of the comet will be respectable. Feels sure Fearon Fallows could not have approved of the supports of the dome. Has been promised the pleasure of inspecting the expenses of the Observatory. Captain J. E. Alexander and Dr. John Murray will call this morning for a parting cup of tea.

Calms TM about not having his comet observations published yet; those published so far are not of much value.

Wants to reset his barometer by TM's.

Asks for TM's barometer and thermometer readings for 20-28 September.

Compares JH's and TM's barometric readings. Criticizes Pierre Morin's work.

Reports on JH's actinometer observations. Explains why he subscribed to 'Col. [Harry] Smith's piece of plate.'

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.'

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