quantity was 130 hundredths of a meafure, viz. one mea- 
fure and thirty hundredths of a meafure more. 
“ The different degrees of falubrity of the atmofphere, 
(fays lie,) as 1 found it in general in my houfe at Southall- 
Green, ten miles from London, from June to September, 
lay between 103 and 109. I was furprifed when, upon my 
return to town to my former relidence in Pall-Mall Court, 
I found the common air purer in general in October than 
I ufed to find it in the middle of fummer in the country ; 
for, on the 22d of Oftober, at nine o’clock in the morn¬ 
ing, the weather being fair and frofty, I found that one 
meafure of common air, and one of nitrous air, occupied 
100 fub-divifions in the glafs-tufce, or exactly one mea¬ 
fure. That very day, at two o’clock in the afternoon (it 
being then rainy weather), the air was fomewhat altered 
for the worfe. It gave 102. October the 23d, it being 
rainy weather, the air gave 102. October the 24th, the 
weatligr being ferene, the air at nine o’clock in the morn¬ 
ing gave 100. October the 25th, the fky being cloudy at 
eleven o’clock in the morning, the air gave 102. At ele¬ 
ven o’clock at night, from five different trials, it gave 105. 
October the 26th, the weather being very dark and rainy, 
the air gave 105, as before.” 
The air at Offend was found by the doftor to be gene¬ 
rally vCry good, giving between 94 and 98. At Bruges, 
the air taken at feven o’clock at night gave 103. No¬ 
vember 8, the air at Ghent at three in the afternoon gave 
103. November 12, the air at Bruffels at feven o’clock 
P. M. gave 105^. The next day the air of the lower 
part of the fame city gave 106 ; that of the higheff ap¬ 
peared to be purer, as it gave 104: which agrees with the 
common popular obfervation. November the 14th, both 
the air of the higheff and that of the lowed part of the 
city appeared to be of the fame goodnefs, giving 103. 1 he 
weather was frolfy. November the 22d, the air of Ant¬ 
werp in the evening gave 109J ; the weather being rainy, 
damp, and cold. November the 23d, the air of Breda gave 
106. The next day about eleven o’clock the air gave 102 ; 
the weather being fair, cold, and inclining to frod. At 
feven o’clock it gave 103. Next day being the 25th, the 
air gave 104; the weather being cold and rainy. The 
26th it gave 103 ; the weather being very rainy, cold, and 
ftormy. November the 27th, the air at the Moordyke 
clofe to the water gave ioi| ; the weather being fair and 
cold, but not frody. This fpot is reckoned very healthy. 
November the 28th, the air of Rotterdam gave 103 ; the 
weather being rainy and cold. November the 29th, the 
air of Delft gave 103 ; the weather being dormy and rainy. 
November the 30th, the air of the Hague gave 104; the 
■weather being cold, and the wind northerly. The fird of 
December the weather underwent a fudden change; the 
■wind becoming foutherly and dormy, and the atmofphere 
becoming very hot. The day after, Fahrenheit’s thermo¬ 
meter (food at 54 0 ; and the common air being repeatedly 
and accurately tried gave 116; and that preferved in a 
glafs phial from tlie preceding day gave 117 ; and that ga¬ 
thered clofe to the fea gave 115. December.the 4th, the 
air of Amfterdam gave 103 ; the weather being rainy, 
windy, and cold. The day after, the weather continuing 
nearly the fame, the air gave 102. December the 10th, 
the air at Rotterdam gave 101 ; the weather being rainy. 
December the 12th, being in the middle of the water be¬ 
tween Dort and the Moordyke, the air gave 109; the wea¬ 
ther being remarkably dark, rainy, and windy. Decem¬ 
ber the 13th, the air of Breda in the morning gave 109 ; 
tlie weather continuing as the day before. And, in the af¬ 
ternoon, the air gave 106A; the weather having cleared 
lip. December the 16th, the air of the lower part of the 
city of Antwerp gave 105, that of the higher part 104; 
the weather being rainy and temperate. December the 
17th, the air of Antwerp gave 107 ; the weather continu¬ 
ing nearly as in the preceding day. December the 19th, 
the air of Bruffels gave 109; the weather being rainy, 
windy, and rather warm. December the 21ft, the air of 
Bruflcls gave 106 j the weather being dry and cold. Tlie 
P H E R E, 
next day the air and weather continued the fame. De¬ 
cember the 23d, the air of Mons gave 104; the weather 
being rainy and cold. December the 24th, the air near 
Bouchain gave 104J ; the weather being cloudy and cold. 
December the 25th, the air of Peronne gave 102D; the 
weather being frofty. December the 26th, the air of Cu- 
villi gave 103; the weather frofty. December the 27th, 
the air of Senlis gave 102A; the weather frofty. Decem¬ 
ber the 29th, the air of Paris gave 103; the weather frofty . 
January the 8th, 1780, the air of Paris gave 100; the wea¬ 
ther frofty. January the 13th, the air of Paris gave 98; 
hard froft. 
Thus far Dr. Ingenhoufz’s obfervations. The abbe 
Fontana, who has alfo made a great number of very ac¬ 
curate experiments upon this fubjeCt, gives his opinion in 
the following words: “ At Paris, I examined the air of 
different places at the fame time, and efpecially of tfiofe 
fituations where it was moll probable to meet with infedffed 
air, becaufe thofe places abounded with putrid fubftances 
and impure exhalations; but the differences 1 obferved 
were very fmall, and much lefs than what could have been 
fufpefted, for they hardly arrived at one-fiftieth of the 
air in the tube. Having taken the air of the hill called 
Mount Valerian, at the height of about 500 feet above the 
level of Paris, and compared it with the air of Paris ta¬ 
ken at the fame time, and treated alike, I found the for¬ 
mer to be hardly one-thirtieth better than the latter. In 
London I have obferved almoft the fame. The air of If- 
lington and that of London futfered an equal diminution 
by tlie mixture of nitrous air; yet the air of Iflington is 
efteemed to be much better. 1 have examined the air of 
London taken at different heights (for inftance, in the ftreet, 
at the fecond floor, and at the top of the adjoining hou- 
fes), and have found it to be of the fame quality. Hav¬ 
ing taken the air at the iron gallery of St. Paul’s cupola, 
at the height of 313 feet above the ground, and likewife 
the air of the ftone gallery, which is 202 feet below the 
other; and, having compared thef'e two quantities of air 
with that of the ftreet adjoining, I found that there was 
fcarcely any fenfible difference between them, although 
taken at fuch different heights. In this experiment a cir- 
ctimftance is to be confidered, which mu ft have contribu¬ 
ted to render the above-mentioned differences more fenfi¬ 
ble: this is, the agitation of the air of the cupola; for 
there was felt a pretty brifk wind upon it, which I obfer- 
ved to be ftronger and ftronger the higher I afcended ; 
whereas in tlie ftreet, and indeed in all the ftreets I paffed 
through, there was no fenfible wind to be felt. This ex¬ 
periment was made at four in the afternoon, the weather 
being clear. The quicklilver in the barometer at that 
time was 2S - 6 inches high, and Fahrenheit’s thermometer 
flood at 54 0 .” " . 
After mentioning fome other experiments, M. Fontana 
proceeds thus: “From this we clearly fee, how little the ex¬ 
periments hitherto pubiilhed about the differences of com¬ 
mon air are to be depended upon. In general, I find that 
the air changes from one time to another ; fo that the dif¬ 
ferences between them are far greater than thofe of the 
airs of different countries or different heights. For in¬ 
ftance, I have found that the air of London in the months 
of September, October, and November, 1778, when treat¬ 
ed with the nitrous air, gave II, I, 1-90, and II, II, 2-25, 
which is a mean refult of many experiments which differed 
very little from each other. The 26th day of November 
laft, I found the air for tlie firft time much better, for it 
gave II, I, i - 8o, and II, II, 2-20; but the 14th of Febru¬ 
ary, 1779, the air gave II, 1 , 1 ’69, and II, II, 2-21; from 
whence it appears, that the air of this 14th of February 
was better than it had been fix months before. There can 
be no doubt of the accuracy of the experiments, becaufe 
I compared the air taken at different times with that which 
1 had firft ufed in the month of September, and which I 
had preferved in dry glafs-bottles accurately flopped.” 
This difference in the purity of the air at different times, 
M. Fontana farther remarks, is much greater than the 
difference 
