224 Proceedings of Philosophical Societies. [March, 



birds, and vegetables. The author, some time since, sent speci- 

 mens of the teeth to various naturalists ; in particular to M. le 

 Baron Cuvier, whose opinion of them coincided with his own, 

 that they belonged to an extinct herbivorous reptile hitherto 

 undescribed. With the assistance of Mr. Clift he had subse- 

 quently compared them with those of a skeleton of the recent 

 Iguana of the West Indies, in the Museum of the Royal College 

 of Surgeons, with which he found them to possess a close 

 affinity; and he details, in this notice, the particular results of 

 the comparison ; adverting, also, to the probable station of the 

 extinct animal in tlie order of Saurians. From the affinity 

 just mentioned, and at the suggestion of the Rev. W. D. 

 Conybeare, he had given it the name of Iguanodoti. On the 

 supposition that the proportions of the parts in the extinct 

 animal were the same as in the recent, Mr. Mantel) infers that 

 the Iguanodon must have exceeded in size even the megalosau- 

 rus, and have been upwards of sixty feet in length. From the 

 fossils associated with its remains, he concludes, that if an 

 amphibious, it was not a marine reptile, but inhabited rivers and 

 fresh-water lakes. Drawings of the teeth and bones of the 

 Iguanodon were annexed to this communication. 



Feh. 17. — Capt. J. Mangles, RN. was admitted aFellow of the 

 Society ; and a paper was read, entitled " An Experimental 

 Inquiry into the Nature of the Radiant Heating Effects from 

 Terrestrial Sources; " by the Rev. Baden Pnvvell, MA. FRS. 



The objectof this pa])eris to investigate an important question 

 relative to the nature of the heating eHiect, radiated or emitted 

 from burning and incandescent bodies. 



The heat from non-luminous sources has been shown by Pro- 

 fessor Leslie to be entirely intercepted by a glass screen ; that 

 from luminous hot bodies, though in a considerable degree in- 

 tercepted, is yet partially transmitted. M. de la Roche has 

 shown, that the part transmitted increases in proportion to the 

 part intercepted, as the body under trial approaches nearer its 

 point of luminosity, or is more perfectly luminous ; and both 

 M. de la Roche, and his commentators, seem disposed to view 

 these results as showing that the effect is due to one simple 

 agent, the principle both of light and heat gradually passing from 

 the state of the latter to that of the former, and in proportion 

 becoming capable of passing through glass. This opinion, how- 

 ever, is not absolutely proved ; and the facts mui/ be explained 

 without adopting it. Luminous hot bodies maj/ give oli" two 

 separate sets of rays, or emanations, one of light possessing 

 an inseparable heating power like the light of the sun, and 

 transmissible through glass; the other, simple radiant heat to- 

 tally stopped by glass. To examine which of these liypothesfis 

 is the true one, was the primary object of the experiments here 



