on the terrestrial Rays that occasion Heat. 483 



136^ Experiment. 



Fire. Crown glass; one side rubbed on emery. 



5 %9i 73i • • • 22| : 6| = ,277 



This glass, so prepared, stops 723 scattered rays of fire-heat. 



137^ Experiment 



Fire. Coach glass ; one side rubbed on emery. 



o' 68 67± 



5 87J- 72! . . . 19I : 4| == ,242 



It stops 758 scattered rays of fire-heat. 



138^ Experiment. 



Fire. Crown glass ; both sides rubbed on emery. 



o' 68i 68 



5 9 2 f 73 • • • 23£ : 5 = ,209 



It stops 791 scattered rays of fire-heat. 



139^ Experiment. 



Fire. Coach glass ; both sides rubbed on emery. 



o' 6y 6y 



5 88 7o-£ . . . 21 : 3f * cor. — ^° == ,146 



It stops 854 scattered rays of fire-heat. 



140^ Experiment. 



p- C Crown glass. "1 One side of each rubbed on 



\ Coach glass, j emery. 



o' 66 66 



5 86 69% . . . 20 : Sw - cor - — • 1° = ,*5* 



These glasses stop 849 scattered rays of fire-heat. 



