As might be supposed from what we know of its founders and their friends the constitution of the society was on the broadest possible basis. “We had nothing to do,” says Priestley, “with the religious or political principles of each other; we were united by a common love of science, which we thought sufficient to bring together persons of all distinctions—Christians, Jews, Mahometans and heathens, Monarchists and Republicans.”
The invitations issued by the host were usually accompanied by some intimation of the nature of the impending symposium. Thus Watt writes to Darwin, under date Jan. 3, 1781:—
“I beg that you would impress on your memory the idea that you promised to dine with sundry men of learning at my house on Monday next, and that you will realise the idea. For your encouragement there is a new book to be cut up, and it is to be determined whether or not heat is a compound of phlogiston and empyreal air, and whether a mirror can reflect the heat of the fire. I give you a friendly warning that you may be found wanting whichever opinion you adopt in the latter question, therefore be cautious. If you are meek and humble, perhaps you may be told what light is made of, and also how to make it, and the theory proved both by synthesis and analysis.”
The discussions of the philosophic convives were not, however, confined exclusively to chemistry.
“The period,” says Mr Carrington Bolton, “was one of great activity in the world of science; Laplace was applying his mathematical genius to the problems of astronomy; Herschel was sweeping the heavens with his gigantic telescopes; Galvani and Volta were laying the foundations of a revolution in electricity; Count Rumford in Bavaria was devoting his great energy to industrial and social economy; Hatton and Werner were geologising in their respective countries; Haüy was systematising the innumerable crystalline forms occurring in nature; the Montgolfier brothers were experimenting with air-balloons and prophesying the yet unsolved problem of aërial navigation; Captain James Cook returned from his memorable voyages around the world, full of adventures and novelties in nature: the application of steam to the driving of land carriages and the propelling of boats was gradually being perfected by patience and genius. These, together with the metaphysical and even the political questions of the day, must have engrossed the attention of the talented friends who dined together at the full moon.”
A picturesque account of the Club is given in Mrs Schimmelpenninck’s Memoirs. Mary Ann Schimmelpenninck (née Galton) was the daughter of Mr Samuel Galton, a wealthy patron of letters and a man of considerable intellectual ability. He was interested in scientific pursuits and was a fellow of the Royal Society. His house at Barr, about seven or eight miles from Birmingham, was a notable place in the social life of the district, and the Lunar Society held some of its most delightful meetings under his hospitable roof, as Mrs Schimmelpenninck recalls. She thus writes of Dr Priestley:—
“A man of admirable simplicity, gentleness and kindness of heart, united with great acuteness of intellect. I can never forget the impression produced on me by the serene expression of his countenance.”
In his Memoirs Richard Lovell Edgeworth says of the Society that it consisted of—
“Men of very different characters, but all devoted to literature and science. This mutual intimacy has never been broken but by death, nor have any of the number failed to distinguish themselves in science or literature. Some may think I ought, with due modesty, to except myself. Mr Keir, with his knowledge of the world and good sense; Dr Small, with his benevolence and profound sagacity; ... Boulton, with his mobility, quick perception and bold adventure; Watt, with his strong inventive faculty, undeviating steadiness and bold resources; Darwin, with his imagination, science and poetical excellence; and Day, with his unwearied research after truth, his integrity and eloquence, proved altogether such a society as few men have had the good fortune to live with; such an assemblage of friends as fewer still have had the happiness to possess and keep through life.”
There can be no doubt that Priestley’s coming to Birmingham contributed greatly to the interest of the meetings of the Lunar Society and reacted beneficially on Priestley himself by stimulating his activity and affording him the sympathy of congenial minds not less interested than he was in the study of natural science. As each meeting came round he was certain to find a gathering curious to hear of his latest experiments and eager to discuss with him their bearing upon the chemical doctrine of the period.