(1^7) 
as to Heat or Cold : Even fo nice, as that my being or not being 
in my Study I find to vary its liight fometimes ahiioft a quarter 
of an inch. 
My Bdf ofcope , I call another Inftrument for eftimatingthe 
IVnght or FrgJ]ure of the Incumbent Air , confifting of a iong 
6lafs-tubeo( about 4. foot in length, and about a quarter of an 
inch Bore: which tube (/;^'f?;2^i^/W/yfeaIed attheoneend)being 
filled with Quickfilver according to the Torricellian Experi- 
ment)is inverted, fo as to have the open end of it immerfed in 
Stagnant Quickfilver, contained in a larger Glafs undent, ex- 
poled to the preffureof the outward Air: Out of which open 
end Cafter fuch immerfion) the Quickfilver in the Tube being 
fuffered to run out, as much as it will, into the Stagnant Qiiick- 
filver, in which that mouth or open end is immerfed, there is 
wont to remain (as is cosimonly known to thofe acquainted 
with this Experiment j a Cylinder of Quickfilver fufpendedin 
the Tube,about 28, 29, or 30. inches high ; meafuring from the 
furfaee of the Stagnant Quickfilver perpendicularly a* (but 
more or lefs, within fuch limits, according as the Weight or 
PrefTure of the Air incumbent on the External Stagnant 
Quickfilver expofed to it , is greater or lefs : ) leaving the up- 
per part of the Tube void. ( Both which Inftrumen'ts being 
the contrivance of the Honourable ^o^^r^^ Boyle , they are by 
him more particularly defcribed in his Phyfieo-Mechanical Expe- 
riments touchingthe Air^Exper, 17. and 18. and in his Thermome- 
tried Difceurfej, premifed to his Hiftory of Celd.y 
Now, according to both thefe Inftruments, havingkepta 
daily T\%tfi^T of Obfervations for more than a whole year ( fa- 
ving when I have been for fome fliort time abfent from home) 
I find my Notes for that day to be thefe. 
January, 
Day. Houn 
19.8. Morn 
' 4. Even. 
9. Even, 
a©. 8. Morn. 
Tbermefcope, 
inches. 
14 i 
14 t 
Barofcope. 
inches. 
09 ^ 
28 t. 
Hard froft. 
Hatdfroft. 
Rain. 
Sunfliine. 
Clofe. 
Cloudy. 
Wind 
Wind. 
So that.there being in the morning (^January 19.) a hard froft 
(which began the day before about 4. of the Clock in the after- 
noon 
