1304.] 
Now give me leave to mention a preju- 
dicial error J have obferved in Nafural Hif- 
tory, by confidering the ant (formica) as an 
injurious infect; for I find her to be very 
ufeful in the dettru&tion of aphides and ca- 
terpillars. ‘Thefe,-while they remain, ‘are 
her only food, and it is but juft that fhe 
fhould be rewarded with a little of the 
fruit fhe has beenthe means of protecting. 
I hope, therefore, Mr. Editor, this will 
induce the humane to take her under their 
protection, and not to regard her as con- 
trary to the wile polity of nature. - 
Tam, Sir, Your obliged fervant, 
Feb-28, 4804. HONECIB. 
To the Editor of the Monthly Magazine. 
SIR, 
ry} ‘HE variations which your meteoro- 
logical Correfpondent in Perthfhire 
oblerved, between his /pzrit of wine ther- 
mometer, aud a thermometer (probably 
a mercurial one) which he borrowed to 
Compare therewith, as related at page 
673 of your laf volume, have fuggetted 
to me the propriety of ftating fome fimi- 
lar circumffances, which occurred in fome 
thermometric experiments which I had 
occafion to make in the year 1801.— 
Among the numerous enquiries into the 
caufe of the extraoidinary fertility com- 
municated to meadows by irrigation, a 
mott intelligent writer has advanced, that 
heat is the principal agent, and that 
water, which has loft a part of its heat, 
by ftanding expofed to a colder atmo- 
{phere, or by pafiing over the furface of 
part of a meadow, will !peedily acquire 
tne neceflary temperature, to be again 
ufed on a lower level, if ic be conveyed 
thereto in {uch a manner as to ruz brifkly 
in a carriage or channel for a certain 
{fpace. It was in order to afcertain the 
truth of this theory, that I began, in 
February, 1801, a feries of experiments 
in the meadows, which were conftructed 
under my direétions for his Grace the late 
Duke of Bedford, near Woburn. The 
thermometer I ufed was a mercurial one, 
attached to a pewter fcale, and fliding 
into a japanned tin cafe, with a glafs fide 
for yeading the degrees. I had another 
. thermometer filled with fpirits of wine, 
attached toa flip of box, on which, be- 
fides the degrees, were ftamped the names 
of a variety of exotic plants oppofite to 
the proper degree of heat for their growth: 
this {pirit thermometer (the bore of whofe 
tube was about three times as much dia- 
mieter as that of my mercurial thermo. 
meter above mentioned) hung up again 
the fouth fide, or jaumb of a window 
looking to the eaftward; and by the 
fide of it the mercurial thermometer, 
when not in ufe in the meadow, was 
Mercurial and Spirit Thermometers compared, 
213 
hung. I always compared the two ther- 
mometers at going out, and on my res 
turn from the meadow, and was furprifed 
to find, that, though they often ftood at 
the fame degree, it was not always the 
cafe; which induced me. to procure 
another mercurial thermometer, nearly. 
fimilar to the one above defcribed, to 
hang conftantly by the fide of the fpirit 
one, and from the 13th February, 1801, 
to the rft March, 1802, I caufed the de- 
grees fhewn on each thermometer to be 
regiitered, viz, at 9h. A. M. at 12h. and 
at 3h. 6h. and gh. P. M. of each day, 
The fiequent comparifons thus made, 
fhewed clearly, thit when the tempera- 
ture had been for fome time the fame, 
the two thermometers ftood precifely at 
the fame degree, but that the fpirit ther- 
mometer was much longer in acquiring, 
or indicating the temperature to which it 
was expofed, than the mercurial thermo- 
meter; and confequently, whenever the 
mercury was rifing the {pirits ftood lower 
than the mercury, and the reverfe when 
the air was growing, or had recently 
grown, colder. I carried on this experi- 
ment fo long, principally with a view to 
afcertain the greateft variations which 
would occur between the two thermo- 
-meters ; and your readers who are curious 
in thefe matters, may not be difpleafed to 
have the following remarks, which pre- 
fent themfelves on examining my journal 
above mentioned. 
ift. At the hour of 9 A. M.—64 times 
the two thermometers exaétly coincided ; 
63 times the fpirits ftood the. -higheft 
({eldom more than 1 or 2 Gegrees) in all 
the remaining 81 obfervations at this 
hour, when both thermometers were noied, 
the mercury ftood the higheft; on the 
6th June this difference amounted to 64° 5 
on the 14th July to 6°, on 26th June to 
52°; on 18th June, anc roth July to 
5°; on 12th April to 44°; ongth Au. 
guft to 4°; on 13th May, 8th June, qth 
and 3:ft July to 33°; on 2d March, 11th 
April, ssth June, and 16th July to 33°; 
on sgth March, 20th April, 25th May, 
and :1th June to 3°, &c. 
2nd. At the hour of 12.—65 times 
the two thermometers coincided; 104 
times the fpirits ftood higheft, and in all 
the remaining 116 obfervations at noon, 
when. both thermometers were noted, 
the mercury ftcod the higheft; the varia- 
tions at this hour never exceeded 43°, and 
in only nine inftances exceeded 3° either 
way. It fhould be obferved, that the -un 
fhone upon this window till near 120’clock. 
ad. Atthe hour of 3 — 40 times the 
two therm=meters coincided ; 65 times the 
mercury ftood the bighelt; and in all 
the remaining 167 oblfervations, when 
