181').] Scieniific Inlelligemc. J53 



and runs into the Atlantic on the coast of Guinea. It will be very 

 singular if this opinion be confirmed. It would be of great ira- 

 portance if the travellers would carry with them a set of portable 

 barometers, in order to deter.Bine the elevation of the country 

 through which they pass. If we knew the elevation of the banks 

 of the Niger, it would be easy to determine whether the opinion of 

 the ancients, that it is a branch of the Nile, be possible or not. 

 Nothing in Alungo Parke's travels would lead us to suppose that 

 the elevation of the banks of this river is great. In that case it 

 must either flow into an inland sea, or discharge itself into the 

 Atlantic. 



III. Communication between the Blind and the Deaf and Dumb. 



Dr. Guillie, Director of the Royal Institution for the Blind, at 

 Paris, by a method of his own invention, has been enabled to 

 establish an immediate and perfect mode of intercourse between 

 blind and deif and dumb persons. These two species of uofor- 

 tunate individuals, between whom nature appeared to have placed 

 insuperable barriers, may, thanks to the ingenious author of this 

 invaluable discovery, henceforward draw near and perfectly under- 

 stand each other. 



The first trial of this ingenious practice was made at a numerous 

 and public meeting, held at Paris, tlie 26th of last August. A 

 sentence was dictated to one of the deaf and dumb, named Masuen, 

 a pupil of the Abbe Sicard, and by him communicated to one of 

 tlie blind, who immediately repeated it in a lo;jd voice: and he in 

 his turn communicated to the deaf and dumb tlie sentence asked 

 by the public, who instantly wrote it on a tablet. 



We are assured that Dr. Guillie intends coming to London in 

 the winter, to make an experiment of his practice before the Royal 

 Society. 



IV. SuAnesfone at Building Hill, Durham. 



I am informed, by Mr. Sowerby, that some of the Building 

 Hill stone retains its foetid odour for years when scraped, while 

 other specimens lose it very soon. This shows us that I was not 

 mistaken when I called it Swinestone, on tiie spot. But the reason 

 why some specimens soon lose their odour remains still to be given. 



V. On the Solar Spectrum. 



(To nr. Thomson.) 

 SIR, 



Since my last communication it has occurred to mc, that if Dr. 



Herschel's jjosition respecting tlie heating rays attendant on the 



prikmatic spectrum stands in need of any couiirination, the well- 



conduc.-ted experiments of Mr. IvC^iie on radiant caloric sui)stan- 



tlate them in a most remarkable maimer. Mr. L. distinctly aftirms 



that he found the greatest intensily, or, as I should call it, the 



focus of heat, by his reflectors, half an incii within, or nearer to 



the inuTor than, the optical Jwut. As far as I can judge too, fi'om 



