Sir William Hamilton's Vesuvian apparatus

Apollo, May, 2004 by Bent Sorensen

Two eyewitnesses give some clues to the visual impact on the spectators when the transparency was set up in the British Museum. Matthew Maty MD, FRS (1718-76), Secretary to the Royal Society and Principal Librarian of the British Museum, reported that: 'The Picture [...] by the hints you were pleased to give me, makes now a very free appearance in one of our rooms, and gives to the beholders the most striking representation of that awfull phenomenon which you have with such resolution and constancy observed, and so minutely as well as philosophically accounted for and described'. (11) Sir John Pringle MD, FRS (1707-82), afterwards President of the Royal Society, wrote that: 'The representation of that grand & terrible scene, by means of transparent colours, was so lively and so striking, that there seemed to he nothing wanting in us distant spectators but the fright that everybody must have been fired with who was so near'. (12)

The absence of any allusion in the documents to a mechanical contrivance could signify that it was simply a painted transparency, but Maty's statement that the installation had to be made according to 'the hints you were pleased to give me' appears to signify that it was something more. It is therefore uncertain whether the painting in transparent colours mentioned by Hamilton in 1767, was at the outset part of a complete Vesuvian apparatus or whether it was only subsequently that the apparatus was made to enhance the effects of the painting. That Hamilton, at least later, clearly envisaged these transparencies as part of a complete apparatus is suggested when he presented not only a transparency but also a description of the apparatus to the great actor David Garrick (1717-79). At the sale in 182.3 after the death of his widow Eva Maria Garrick, nee Veigel (1724-1822) one lot contained not only Pietro Fabris's 'A view of an eruption of Mount Vesuvius, a transparency, painted under the direction of Sir William Hamilton, and by him presented to Mr. Garrick', but also "A Letter from Sir William Descriptive of a mechanical contrivance to heighten the effect of the eruption, [which] will he given the Purchaser'. (13)

Although these transparencies and the apparatus must have immensely pleased, there are only a few allusions to them. The earliest may be a vague indication in Elisabeth Duchess of Beaufort's diary, where she wrote that on one evening in April 1773: 'we went to Sir Wm Hamilton's where we saw several Electrical Experiments & an Representation of M. Vesuvius as it appeared at the Eruption of 1767'; (14) the fact that it was singled out may indicate that it was something out of the ordinary. However, the only description seems to be the above-mentioned letter from Hamilton to Garrick, which has yet to be located, and the recently discovered document. This is a single sheet with a schematic sketch and a detailed explication of the apparatus by the French naturalist Francois de Paule Latapie (1739-1823), (15) made during his travels in Italy in 1776 (Fig. 4; for a transcription of the French text see opposite). The sketch offers only a crude view of the apparatus but allows us nevertheless to comprehend its workings despite the author's conspicuous misapprehensions of many technical details. It is, to my knowledge, the only known detailed description of any of these entertainments which explains not only how it was perceived but also how it functioned.