1796.) : 
Io the Editor of the Monthly Magazine. 
SIR, | 
ALTHOUGH your correfpondent 
"™ Oriens feems to have propofed his 
queries .relative to Halos for the con- 
‘fideration of M. of Chichetter, alone, 
yet I hepe it will not be deemed impro. 
per for any other perfon who thinks 
what he has to offer on the fubjeét worth 
attention, to communicate his remarks, 
in order that the public may judge of 
their propriety. o 
Oriens atke, “ whether thefé appear- 
ances about the fun and moon are not 
eccafioned by the reflection of the earth’s 
circumference ?”? I mutt confefs, that I 
am not able to conceive how an hypo- 
thefis can be formed on this principle, 
which will fatisfactorily, account for the 
phenomena. Inftead of offering a mul- 
tiplicity of arguments, I fhall relate an 
example :. 
On the xrsth of laft. March, at 02 
P.M. 1 obferved a very curious halo. 
The evening was remarkably ferene,’ 
and the fky free from clouds; excep: in 
the fouth-weft, where a cloud of a light 
colour (nearly white) and of fuch a na- 
ture that ftars of the fecond magnitude 
appeared through it, juft reached up to 
the apparent place of the moon. Around 
the lower part of her difc, and at about 
the diftance of ten of her apparent dia- 
meters, there was refracted upon the- 
clond a luminous arch of a femicircular 
form, having greatly the appearancé of 
an inverted rainbow, fetting afide the 
difference of fize. The colours, red, 
erange, and yellow, were tolerably well 
defined; the green was fomewhat con- 
fufed, and the other colours were fcarce- 
ly diftinguifhable. This beautiful ap- 
pearance I obferved for about ten mi- 
nutes : at length the cloud thifted its fi- 
éuation, and the halowas deftroyed. 
ts this to be accounted for ina fatif- 
factory manaer, on the fuppofition that 
the light cloud was the agent for re- 
fecting the earth’s circumference, and 
thereby forming a bow under the Mcon? 
I think not, Nor do I think it very 
probable, that any hypothefis will be 
fpeedily invented, which will ferve bet- 
ter to account for thefe phenomena, than 
ene which may be derived from confi- 
dering the refrangibility of the rays of 
fight, and the difpofition of clouds and 
vapours. fufpended in the air, to produce 
Fetraction... 
» [he tecend query of Oriews, fo far as 
at is connected with the firft, may, per- 
Mr. Grezory on Elalos. . . Lime. 
haps, be fet afide: but to determine 
whether appearances of this kind -gene- 
rally prognofticate rain, may require 
more obfervations than have yet been 
made, or are likely to be made at pre- 
fent. When it is confidered, that the 
air being more loaded with fome pecu-. 
liar kind of vapour, may fo much change 
its power of refragting as to produce 
halos, it will not feem improbable, that 
thefe appearances fhould precede fome 
change of weather : but as meteorology ig 
yet but in its infant ftate, we muft not 
be too fanguine in fuppoiing, that a ge- 
eral rule for judging of the weather 
likely to follow any particular phenome- 
non can be given, until obfervations for 
a_feries of years have been made, and 
properly regiftered ; and even then, the 
inferences which may be drawn from 
the journals muft be received with 
caution, fince many adventitious circum- 
flances may occur, which may render 
the obfervations of years of bat little 
utility in determining the point. 
Previous to concluding, I muft remark, 
that if any of your corre{pondents fhou’d 
think my obfervations in any refpect — 
wrong, I hope they will have the good- 
nefs candidly to place my blunders in 
view. I aman advocate for free difcuf= 
fion, and with to fand convitted of any 
error £ may fall into. 
Your's refpecifully, 
O. G. GREGORY 
Yasley, O. 6, 1796. 

To the Editor of the Monthly Magazine. 
SIR, 
your correfpondent T. who has fa- 
voured the public, in your Third 
Number, with his opinion on the Quali- 
ties of Lime, as a manure ; inferring, that 
ia confequence of a fuppofed feptic 
power, it becomes favourable to vegeta- 
tion ; and this idea being queftioned by 
your correfpondent T. P. in your Eighth 
Number, who doubts the /eptic quality, 
and attributes the advantage of lime, as a 
manure, to its caufticity-; induces me ta 
trouble you with my ideas on the fubjeét. 
If Terr in my theory, I fhall be glad 
either of thefe correfpondents, or others, 
will correét my hypothefis; in either 
eate, the public will be informed, through 
the medium of your very ufeful Maga- 
Zine. 
It appears by experiments, that fixed 
air is highly favourable to vegetation, 
therefore means which produce ‘an. in- 
crealed fupply to the land, muft be ad- 
yantageous, 
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