Experivients on the Rays which occajion Heat. 253 

 the. natives, they compelled him to take upon his back a 

 young wolf they had found, and to return with them to a 

 village which he had left only a few hours before. Here he 

 was detained eight days, during which he fuffered considerably 

 from the wound in his foot ; but being at length fuffered to. 

 depart, and proceeding towards the territories of the Seege- 

 rians, he arrived at a village called Mukofa, fituated en an 



eminence. 



[To be continued.] 



VI. Experiments on the Solar and on the Terrejlrial Rays that 

 occafion Heat ; with a comparative View of the Laws to 

 which Light and Heat, or rather the Rays which occafion 

 them, arefubjed, in order to determine whether they are the 

 fame, or different. By William Herschel, LL.D. 



"f.r.s. 



[Continued from Page 134.J 

 14/y Experiment. Refraction of the Heat of a Chimney-Fire. 



1 PLACED Mr. Dollond's lens before the clear fire of a 

 large grate *. Its diftance from the bars of the grate was 

 three feet; and in the fecondary focus of it was placed the 

 thermometer No. I. No. 4 was Stationed, by way of Stand- 

 ard, at al- inches from the former, and at an equal diftance 

 from the fire. Before the thermometers was a flip of maho- 

 gany, which had three holes in it, & of an inch in diameter 

 each. Behind the centre of the firft hole, | of an inch from 

 the back, was placed the thermometer No. 1 ; and between 

 the fecond and third hole, guarded from the direft rays of the 

 fire by the partition, at the fame diftance from the back, was 

 put No. 4. Things being thus arranged, the Situation of the 

 apparatus which carried the thermometers, and that where 

 the lens was fixed, were marked. Then the thermometers, 

 having been taken away to be cooled, were reftored to their 

 places again, and their progrefs marked as follows : 



* See Plate VIII. fit", j. 



No. 



