1802.] 
ment than they could obtain without our 
affiftance, the philofophical agricultor fir 
eonfiders what kinds of matter are moft 
prevalent, or moft neceffary in their com- 
polition: fecondly, what of thefe fub- 
ftances they can abforb without previous 
decompofition: and laftly, how to expe- 
dite that procefs when it becomes necef- 
fary. A valuable feétion fucceeds on 
dcaining and watering lands: here fome 
ufeful hints are thrown out for detecting 
the fituation of {fprings, and for convey- 
ing away the water from thofe plains and 
moraffes where there is no obvious channel 
for its efcape: the benefits of flooding Jand 
are enlarged on; fome neceflary cautions 
introduced refpecting the procefs, and fug- 
geftions made for the extenfion of the 
practice, not only by taking advantage of 
the natural fails of brooks and fprings, 
and by occafionally damming them up to 
fupply higher fituations, but by the ufe 
of various machinery. 
A feétion on the aeration and pulveriza- 
tion of the foil fucceeds, in which the ufes 
of fallowing are philofophically eftimated, 
and the management of the wheat-crop 
enlarged on. The tranfplantation of 
wheat is here recommended in a very un- 
qualified manner: we have ourfelves tried 
it, on a fcale of between four and five 
acres, with complete fuccefs. 
The fucceeding fection treats on Light, 
Heat, and Eleétricity: under the laft of 
thefe three heads one cannot but {mile at 
the ‘* profitable application of eleétricity’” 
which is intimated to the gardener or the 
agricultor: as the oxygen of hydrogen 
gaffes may exift in the fummer atmo/phere 
in a ftate of mixture, but not of combina- 
tion, and as the electric fpark or flafh of 
lightning may ‘combine them and produce 
water inftantaneoufly, ‘it is probable that 
in dry feafons the ereftion of numerous 
metallic points on the furface of the 
ground, but a few feet high, might in the 
night time contribute to precipitate the 
dew by facilitating the paffage of electri- 
city from the air into the earth; and that 
an erection of fuch points higher in the air, 
by means of wires wrapped round tall 
rods, like angle rods, or elevated on 
buildings, might frequently precipitate 
fhowers from the higher parts of the at- 
mofphere.” An interefting and valuable 
feftion on the difeafes of plants, concludes 
the fecond part: thefe difeafes are divided 
into thofe which appear to originate from 
internal caufes, thofe from the external 
elements, and thofe from the nidification 
Biographical Memoirs of the late Dr. Darwin, 
461. 
or depredations of infeéts: to which 1s 
added, the deftruction by vermin. Under 
the third head is given a very curious 
account of the aphis, together with various 
methods for deftroying it; and the inge 
nious one is fuggefted of propagating its 
greateft enemy, the larva of the aphidivo- 
rous fly, and thus devouring one infect by 
the means of another. 
The third part of the Phytologia, on 
agriculture and horticulture, is divided 
into fix feétions: the firft treats on the 
produétion of fruits; in which the four 
methods are enlarged on of procuring 
fruit trees for the purpofes of horticulture, 
by feeds, by root-fuckers, by planted 
fcions, and ingrafted fcions: the author 
next proceeds to fhew how a tree may be 
neceflitated to increafe the number of 
flower-buds, in preference to its leaf-buds. 
The means of perfecting, enlarging, and 
preferving fruit are then feverally infifted 
on. The important fubjeét of the produc- 
tion of feeds occupies the next fection; 
in which rules are laid down for producing 
them early, and in great quantity—for 
ripening them—for generating the beft 
kinds—for collecting good feeds and deter- 
mining their goodnels—for the preferva- 
tion of feeds, and for fowing them advan. 
tageoufly. The two next fections treat, 
one on the produétion of roots and barks, 
and the other on the produétion of leaves 
and wood: and the laft contains a plan 
for difpofing part of the vegetable fyitem 
of Linnzus into more natural claffes and 
orders. The plan here fuggefted, of 
adopting the fituations, proportions or 
forms, with or without the numbers. of 
the fexual organs, as criterions of the order 
and claffes, is well worthy the attention of 
botaniits. While the number of ftamina 
and piftilla are fubject to variation, both 
from luxuriant and deficient growth, im- 
plicit confidence cannot be placed on that 
alone, as indicative either of an order or 
clafs. As the proportions and figures and 
purpofes of the ftamina and piftilla are 
immutable, Dr. Darwin imagines they 
would form a preferable ftandard, both 
for claffical and ordinal arrangement. 
But it is time that we fhould confider 
Dr, Darwin in his third charaéter, name- 
ly asa Poer. Dr. Darwin lately fad to 
a friend, that in his poetical woiks his 
great aim was to prefent an object to meet 
the eye, and that he was not anxious to 
touch the heart. A more (evere criticifm 
could icarcely have been pronounced; 
there is, notwithftanding, a juitne{s in the 
remark 
302 
