112 



years of age. In these cases the excrescence was a tumour no larger 

 than a pea, but the appearance of which threatened the formation of 

 a cancer. Both these were successfully removed by the ligatures 

 above described ; and, except a small fissure, no kind of deformity 

 was left upon the tongue. 



The principal inference derived from these operations is, that the 

 internal structure of the tongue is less irritable than almost any other 

 organized part of the body ; and that therefore the peculiar substance 

 which is interposed between the fasciculi of its muscular fibres is not 

 in any respect connected with the nerves which pass through its 

 substance to the organ of taste, but is merely a soft medium, which 

 is intended to facilitate the action of the organ in its different parts. 

 It also appears from these observations, that the nerves of the tongue 

 may be more easily compressed and deprived of their power of com- 

 municating sensation than nerves in general ; and that an injury in- 

 flicted on them is not productive of any diseased action in the trunk 

 of the injured nerve. 



Lastly, the advantages to be derived in the practice of surgery 

 from the success of these operations, are briefly stated ; and indeed 

 the removing with safety the whole part of a tongue which may have 

 taken on a disposition to be cancerous, will easily be allowed to be a 

 most material improvement in that important branch of the medical 

 profession. 



Observations of the Transit of Mercury over the Disc of the Sun ; to 

 which is added, an Investigation of the Causes which often prevent 

 the proper Action of Mirrors. By William Herschel, LL.D. F.R.S. 

 Read February 10, 1803. [_Phil. Trans. 1803, p. 214.] 



Concerning the transit of Mercury, as the times at which the ob- 

 servations were made were not the chief object of the investigation, 

 the detail here given is only to be considered as denoting the order 

 of their succession. When the planet was first seen on the disc of 

 the sun on the 9th of November last at about 40' after seven in 

 the morning, it was easily distinguished from the openings in the 

 luminous clouds generally called spots, its perfect roundness being 

 sufficient to point it out, had its place not been previously known. 

 As the morning advanced, its termination became by degrees still 

 more accurately defined ; and the corrugations of the luminous sur- 

 face of the sun were visible up to the very edge of the planet. Near 

 the egress, when the sun and planet were nearly in the meridian, 

 particular attention was paid to the appearance that was thought to 

 indicate an atmosphere round Mercury ; but nothing of the kind 

 could be perceived, its periphery remaining sharp and well defined 

 to the very last. It was also observed that the appearance of the 

 planet, during the whole transit, never deviated in the least from the 

 spherical form ; whence it is inferred, that unless its polar axis should 

 have happened to be situated in a line drawn from the eye to the sun, 

 the planet cannot be materially flattened at its poles. 



