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.'

Reports in detail JH's observations of Halley's Comet as observed from the Cape of Good Hope.

Discusses methods of magnetic observation, JH's actinometric readings in the Cape, and the need for more physical observatories.

Some geological samples have been lost on the way to England; JH comments on his ideas of the effect of the earth's hot core on the construction of the earth's crust.

Comments on inaccuracies in earlier Southern Hemisphere star catalogues, along with an extended description of comet observations.

Comments about AD's work in mathematical functions, and then refers to JH's reductions and other astronomical matters, including the need for reform of stellar nomenclature.

Please convey thanks to the Society for the Diffusion of Useful Knowledge for its star maps. Finds them preferable to [Johann] Bode's maps, 'which are full of egregious errors.'

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.