481 



In Desagulier's Natural Philosophr/ (\76S), an experiment with 

 a balance, similar to Father Secchi's arrangement, is described and 

 figured, but it is not referred to as a construction available for prac- 

 tical purposes. This might lead one to believe that the contrivance 

 was more recent than Desagulier's time. But, after considerable 

 search, I found, in the nineteenth volume of Rozier^s Observations de 

 Physique (1782), page 346, a curious historical statement by 

 Magellan, which refers the contrivance to Sir Samuel Morland, who, 

 it is there stated, presented it to Charles II. Magellan does not, 

 however, give his authority for this, stating, on the contrary, that he 

 found no mention of the contrivance in any of the authors who had 

 treated of the subject, but that he had seen two of these instruments. 

 One of them, made by Adams in 1760, belonged to George III.; 

 and I think it possible that it may still be found amongst the in- 

 struments of the Kew Observatory. The other was made by the 

 celebrated Sisson, and came into M. Magellan's possession ; a care- 

 ful figure of it is given in the work just cited. It is perhaps likely 

 that the ascription of it to Morland, and the story of its presenta- 

 tion to Charles II., was a tradition among the London instrument- 

 makers. It may, however, be recorded in some of Sir Samuel Mor- 

 land's writings, which I have not found either in the College or the 

 Advocates' Library, and in which it does not appear that Magellan 

 had himself seen it. 



I have as yet been unable to trace the steelyard modification of 

 the statical barometer to its origin. I think it likely to be an in- 

 dependent invention. 



Of course these remarks are not intended to infer the smallest 

 doubt on Father Secchi being the inventor of the instrument which 

 he describes. Of that there can be no question ; and the application 

 of it, which Father Secchi proposes, to the purposes of self-registra- 

 tion, makes it a well-timed resuscitation of an almost forgotten con- 

 trivance, which yet appears to date from the same century with the 

 invention of the barometer. 



2d March 1857. 



Postscript — 16th March 1857. — I have not succeeded in throwing 

 any further light on the true origin of the statical barometer. On 

 writing to Mr Welsh of the Kew Observatory, I find that King 

 George III.'s curious collection of apparatus has been long dispersed. 



