242 



PHILOSOPHICAL TRANSACTIONS. 



[anno i7g'2. 



dually more rarefied regions of its atmosphere, must extend far above its highest 

 mountains ; it is yet a fact that the breadth of this observed twilight, to where 

 it loses itself in our reflected terrestrial light, does not measure more than 2° 34': 

 it is therefore highly probable that its greatest extent, in the most favourable 

 phases near our new moon, can never exceed the double of the above arc, or 

 5° 8' ; and hence we can only infer a perpendicular height of an atmosphere 

 capable of inflecting the solar rays, which at most measures 5376 feet : nor is it 

 very likely that, unless accidental, and hitherto unknown circumstances should 

 occasionally condense different parts of this atmosphere, these upper strata should 

 materially affect the distinctness of a star seen through it. 



But admitting the height of the atmosphere, which may affect the brightness 

 of a fixed star, not to be less than 5376 feet, this will amount to an arc of only 

 0".Q4, or not quite 1 second ; and as the moon describes an arc of l" in 2* of 

 time, it follows that in general the fading of a star, which approaches to an 

 occultation, cannot last quite 2^ in time ; that if the appulse be at a part of a 

 limb of the moon where a ridge of mountains interferes, the gradual obscuration 

 will last a still shorter time ; and that it may, under some circumstances of this 

 nature, be even instantaneous. 

 XVII. Abstract of a Register of the Barometer, Thermometer, and Rain, at 



Lyndon, in Rutland. By Thos. Barker, Esq.; with the Rain in Surrey and 



Hampshire; for 17QI. p. 362, 



Thermometer. il Rain. 



Jan. 



Feb. 



Mar. 



Apr. 



May 



June 



July 



Aug 



Sept. 



Oct. 



Nov. 



Dec. 



Barometer. 



Highest. 



Mom. 



Aftern. 



Morn. 



Aftern. 



Morn. 



Aftern 



Mom. 



Aftern. 



Morn. 



Aftern. 



Morn. 



Aftern. 



Morn. 



Aftern. 



Morn. 



Aftern.! 



Morn. 



Aftern. 



Morn. 



Aftern. 



Morn. 



Aftern. 



Morn. 



Aftem. 



locbcs. 



29.92 

 29.96 



30.11 



29.65 

 29.91 



29.78 



29.SO 



30.06" 

 29.88 

 30.00 

 29.80 

 29.88 



Lowest. I Mean. 



Hig. 



29.38 



In the House. 



44^ 



46 



48 



48 



51 



53 



56 



58 



57 



59 i 



67 1 



7"i 



66 



69 



69 



71 



65 i 



69 



57 h 



5Sh 



48, 



49 



44 



44 



Low 



36 

 36 



37 h 

 38 

 38 

 40 

 46 

 46^ 

 45 

 46 

 52 

 53 

 56| 

 58 

 55i 

 57' 

 53 

 54 

 44 

 45 



38 i 

 41 

 20 

 29 



Mean 



40^ 



41' 



41 J 



42| 



45 



46 



50l 



52 



51 



53 



09 



61 



60 



64 



62 



63 h 



58| 



60 



501 



51,4 



44 



45 



36 



37 



Hig. 



Abroad. 



48 .J 

 51' 



491 



56 



53,^ 



65 



53 i 



68' 



64 



80 



631 



79i 



67 



,soi 



64 



72 



57 



65 



50 



5H 



41 



46i 



Low 



28.^ 



35 



28 



J7 



39 h 



45| 



38 



43i 



43 



52 



5U 



56 



49 



58 



43 



55 



30;^ 



ill 



35 



3()' 



16 



25i 



Mean 



37 



42^ 



39 



17 d 



45 



56 



47 



57 



53^ 



66 



56 



67 



58 



68 



53 



63 



43 i 



52' 



40 



44J 



31 



35 



Lyndon 



2.410 

 1.268 

 0.813 

 1.934 

 1.140 

 0.921 

 4.033 

 2.907 

 0.596 



3.319 

 4.231 

 1.150 



50i 



24.722 



Surry. 

 S. Lamb 



Inch. 

 2.91 



2.29 



0.92 



1.57 



0.76 



0.60 



2.76 



1.26 



0.27 



2.33 



3.44 



1.44 



20.46 



Hampshire. 



Selbourn 



Inch. 



6.73 

 4.64 

 1.59 

 1.13 

 1.33 

 0.91 

 5.56 

 1.73 

 1.73 

 6.49 

 8.16 

 4.93 



44.93 



Fy field. 



Inch. 



3.82 



1.81 



0.90 



0.991 



0.59J 



0.71 



3.45J 



1.92 



0.77 



3.06J 



3.86J 



2.15 



24.05i 



