Mr Dunn*s Improvement of Butherford^^ Thermometer. 279 



rivulets, and inclosing subapennine fossils of the most delicate 

 structure. 



De Saussure, after having described these hills and alpine 

 detritus, adds the following reflections : " Do not these two 

 hills which converge under an angle of about 100°, at the en- 

 trance of the vale of Aosta, evidently mark out the margins 

 of a current which became widened on issuing from this val- 

 ley \ I know not whether I am giving way to an illusion, but 

 it appears to me, that, in the want of the testimony of ocular 

 witnesses, we cannot imagine monuments more forcibly pro- 

 ving the truth of a fact." Notwithstanding the entire con- 

 viction of our celebrated geologist, the founder of the theory 

 of glaciers, I am almost disposed to believe that the partisans 

 of new doctrines respecting moveable rocks or boulders, will 

 see in these hills a classical example of the colossal grandeur 

 of ancient moraines, and that, if they happen to examine the 

 moutonnees and striated surfaces in the neighbourhood of Ivree 

 they will declare their conviction that the ancient glacier, of 

 which we discovered traces at St Vincent, had extended as far 

 as the edge of the great plain of Piedmont.* 



Description of an Improvement on HutherforcTs Registering 

 Thermometer. By Mr John Dunn, Optician, Curator to the 

 Society of Arts.t Communicated by the Society of Arts. 



The maximum and minimum registering thermometers of 

 Rutherford are not only the simplest, but by far the best yet 

 invented ; indeed, all that is required in their construction, 

 beyond an ordinary mercurial thermometer for the maximum, 

 and a spirit of wine one for the minimum, is, to place them 

 horizontal, and introduce into each a small index, in the one to 

 be pushed up by the mercury, and to be dragged down by the 

 alcohol in the other. No difficulty has been felt in executing 



* Bulletin de la SociHi Ocologiquc de France for February 1840. 

 t Read before the Society of Arts for Scotland, loth January ia40. 



