CANA L. 
wholly formed of earth, the additional expence of con- 
ftrufting a lock upon this principle may be i neon ii doable, 
and the"delay (if due attention be had to the above par¬ 
ticulars) very trifing-; it is believed to be an obje'dt well 
worthy the a' eanon of all pet funs interefled in canals. 
Many other inventions have recently been fuggefled for 
tlie improvement of canal navigation, and particularly for 
lowering and elevating boats from one level to another 
without the affiftance of locks. Dr Anderfoh, in Scot¬ 
land, has invented a plan which he deferibes as follows: 
“ You are to fuppofe that fig-6, in the preceding Plate,- 
reprefents a bird’s-eye view of this apparatus. A, is fup- 
pofed to be the upper reach of the canal, and B, she low¬ 
er reach, with the apparatus between the two. This con- 
fifts of three divifions ; the middle one, extending from C 
to D, is a folid piece of mafonry, raifed frony a firm foun¬ 
dation below the level of the bottom of the fecond reach : 
this is again divided into five parts, viz. d, d, d, where the 
wall rifes only to the height of the water in the upper 
reach, and e, e, t«o pillars, raifed high, enough to fupport 
the pivots of a wheel or pulley g, placed in the politjon 
there marked. The fecond divifion h, confifts of a wood¬ 
en coffer, of the fame depth nearly as the water in the 
upper reach, and of a fize exactly fitted' to contain one of 
the boats. This communicates, diredtly with the upper 
reach, and, being upon the fame plane with it, and fo 
connected as to be water-tight, it is evident, from infpec- 
tion, that nothing cat) be more eafy than to float a boat 
into this coffer from the upper reach ; the part of the 
wheel that projects over it being at a fufficient height a- 
bove it, fo as to occation no fort of interruption. 
“ In the third divifion, at i, is reprefented another coffer, 
precifely of the fame dimenfions with the firft ; but here, 
two fluices which were open in the former, and only re¬ 
prefented by dotted lines, are fuppofed to be Unit, fo as 
to cut off all communication between the water in the ca¬ 
nal and that in the coffer. As it was impofiible to repre- 
fent this part of tiie apparatus on fo final! a fcale, for the 
fake ofillufiration it is reprefented more at large in fig. 9, 
where A, as before, reprefents the upper reach of the ca¬ 
nal, -and h one of the coffers. The fluicc k goes into two 
cheeks of wood, joined to the mafonry of the dam of the 
canal, fo a_s to fit perfectly clofe; and the fluicey fits, 
equally clofe into cheeks made in the tide of the coffer for 
that purpofe; between thefe two fluices is a fmall f'pace 
0. The coffer, and this divifion 0, are to be fuppofed full 
of water, and ir will be eafy to fee that thefe fluices may 
be let down, or drawn up, ar pjeafure, with much facility. 
Fig. 10, reprefents a perpendicular feCticn of thefe parts, 
in the fame direction as in fig. 9, and in which the fame 
letters reprefent the fame pans. 
“ Things being' thus arranged, you are to fuppofe the 
coffer li to be fufpended, by means of a chain palled over 
the pulley, and balanced by a weight, that is fufficient to 
counterpoife it, fufpended at the oppolite end of the chain. 
Suppofe then, that the counterpoife be made fomevvhat 
lighter than the coffer with its contents, and 1 hat the line m, 
n, fig-10, reprefents a divifion between the folid fides of the 
dam of feparation, w hich terminates the upper reach, and 
the wooden coffer, which had been doled only by the 
preffnre of its own weight, (being pufned a very little, 
from A towards B, beyond its precife perpendicular 
fwing,) and that the joining all round is covered with lifts 
of cloths put upon it for that purpofe; it is evident that, 
fo long as the coffer is fufpended at this height, the join¬ 
ing mult be water-tight, but no fooner is it lowered down 
a little than this joining opens, the water in the fmall di¬ 
vifion 0 is allowed to run out, and an entire feparation is 
made between the fixed d,am and this moveable coffer, 
which may be lowered down at pleafi-te without lofing 
any part of the water ir contained. Suppofe the coffer 
now perfectly detached, refer- to fig. 7, which- reprefents 
a perpendicular fection of this apparatus, in the direction 
of the -pptted line p, p, fig. 6. In fig. 7, h reprefents an 
end view of tiy: coffer, indicated by the.fame letter as in 
fig. 6, fufpended by its chain; and now perfectly detm he 1 
from all other objects, and balanced by a.coimtei po>fe 
which is ano-tlVe. coffer exactly of the fame fixe, as low- 
down as the level of the lower reach. From inflection t 
is evident, that, in proportion as the - ore cf thel’e wmgh's 
riles, the-other mu ft defeend. For the prefent then, hip- 
pofe that the coffer h is by fonte means rendered more 
weighty than 4 , it is plain it will defeend while the other 
rifes; and they will thus continue till h comes down to 
the level of the low er reach, and i rifes to the level ot the 
higher one. Fig. 8, reprefents a feClion in the chreChon 
A, B, (fig. 6,) in which the coffer i (feen.in both fitua- 
tions) is fuppofed to have been gradually raifed from the 
level of the lower reach ; B, to that of - the. higher ; A, 
where it now remains fiationafy ; while the coffer h ( which 
is concealed behind the mafonry) has defeended in the 
mean time to the level of the lower reach, where it clofes 
by me. ns of the juncture r, s, fig. to, (which juncture is 
covered with hits of doth, as before explained at to, k, 
and is of courfe become water-tight,) when, by lifting the- 
11 nice t, and the coi refpopding fluice at the end of the ca¬ 
nal, a perfect communication by water is effablifhed be¬ 
tween tlielri. If then, inflead of water only, this coffer 
had contained a boat, floated into it from the upper reach, 
and then lowered down, it is very plain, that when thefe- 
fluices were removed, after it had reached the level of the 
lower reach, that boat might have been floated out of the 
coffer with'as much facility as it was let into it above. 
Mere then we have a boat taken from the higher into the 
lower ca;ial; and, by reverfing this movement, it is very- 
obvious that ; t might be, with equal eafe, raifed from the- 
lower into the higher one. It now only remains that I 
fhould explain by what means the equilibrium between- 
thefe counter-balancing weights can be deffroyed at plea- 
fure, and the motion of pourfe produced. It is very evi¬ 
dent, that if the two correfponding coffers be precifely of 
the fame dimenfions, their weight will be exaCtly. the fame 
when they are both filled to the fame depth with water. 
It is equally plain, that fhould a boat be floated into either- 
or both of them, whatever its dimenfions or weight may 
be, fo that ir can be contained aflo.at in the coffer, the- 
weight of the coffer and its contents will continue precife¬ 
ly the fame as when it was filled with water only ; hence 
then, fuppofing one boat is to be lowered or one to be rai¬ 
fed at a tune, or fuppofing one to be raifed and another 
lowered at the fame time, they remain perfectly in equi¬ 
librium in either cafe, til! it is your pleafure to deffrov 
that equilibrium. Suppofe then, for tiie prefent, thitt horll 
coffers aid loaded with, a boat in each ; the double fluices 
both above and below clofed ; and fuppofe aifo,. that a: 
flop-cpck u, in the under- edge of the fide of the lower cof¬ 
fer (fig.8 and to) is opened, feme of the water which fery- 
cd to float the boat in the coffer will flow cut of it, and 
confequently that coffer will become lighter than the high¬ 
er one ; the upper goffer will of courfe defeend,. while the: 
other mounts upwards. When a gentle motion, has been 
thus communicated, it may be prevented from accelera¬ 
ting, merely by turning the flop-cock fo as to prevent the 
lofs of more water, and. thus one coffer will continue to 
afeend, and the oilier to defeend, till they have ^flumedit 
their Rations refpeftivejy.; when, in confequenee of a flap 
below, and another above, tlv y are tendered fiationary at 
the level of the refpeplive canals Precifely the fame, ef¬ 
fect will be produced v.hen the coffers are fi.llcd entirely 
with water. 
“ ft is unneceffary to add more to this explanation, ex¬ 
cept to cbferve that the fpace. for the coffer <0 defeend in¬ 
to muff be deeper than the bottom of the lower canal, in. 
order to allow a free defeent for the coffer to the lequffite 
depth ; and of courfe it will be necefl'ary. to have a fmall. 
conduit to allow the water to get out of it. Two or three- 
inches free, below the bottom of the canal, is all that 
would be necefl'ary. Where tiie height is inconfiderable,. 
there will be no-occafion for providing any counterpoife- 
for the chain, as, that will give only a fmall addition to the- 
hi. 
