The Marquess of Rothgar was, of course, very interested in science and engineering, and so he would be reading the Philosophical Transactions of the Royal Society, which was first published in 1665. The word "philosophical" might mislead. It referred to "natural philosophy" which is what we now would call science.
This link will take you to content from 1765, round about the time of the current Malloren books.
The thing I love about this Enlightenment age is the keen desire for knowledge on all matters. This is a partial list of the contents and I've poked into a few to see what was there. You can click on them to read more.
CHINESE PHESANT XIV
CHELSEA GARDENS XV
BUOYANCY OF CORK XVI
ERGOT OF RYE XVII
VOIDED STONE XIX
TWO THEOREMS XXII
SMALL POX XXIV
(This is a statistical account of the beneficial results of innoculation in parts of the American colonies.)
WOOL MANUFACTURE XXV
(A better way to weigh skeins of wool.)
AIR IN WATER XXVI
SALT ON WOUNDS XXVII
(Rattlesnake victims cured by sea salt. Could be of use in someone's novel!)
GREEN HEMLOCK XXIX
(An account of a thunderstorm in Oxford, in which the lighting was red and people felt heat from it. It seems almost supernatural, and could form an interesting element to a paranormal historical. Some war between mages?)
In another issue I found An Account of the Success of the Bark of the Willow in the Cure of Agues.
In other words — what we now know as aspirin or acetylsalicylic acid and its effects on pain.
Do you like to think that the heroes of Georgian romances were probably enjoying such publications and even contributing to them, or does it seem to geeky?