340 
Turnpike Roads* 
stances doubled by using it. The theory of its action was not uu- 
, derstood. Judge Peters of Philadelphia, who first collected 
the opinions of our farmers, on the subject of the gypsum as a ma- 
nure, ventured to suggest, that the vitriolic acid was the fertilizing 
principle of this manure : But Mr. Priestley of Northumberland, 
has given this opinion a fair trial, both by means of sulphur, and of 
sulphuric acid, in all proportions, without the slightest appearance 
of success. We shall have therefore as I think, to recur to the 
theory first advanced by myself in the year 1793, that it acts as a 
septic to dead fibres, and as a stimulus to living ones. 
Manures of moisture and Mechanical manures. Their action 
in giving depth by new addition; in giving tenacity by mixture, 
as clay with sand, or vice versa... .in giving capacity to retain mo ~ 
isture , on the principles suggested by the experiments o£Fabro- 
hi and D’Arcet, is too obvious to require further elucidation. 
Such are the ideas that occur to me as throwing some light on 
the theory of this complicated and most important subject, and sug- 
gesting the rationale of the application of manures, in cases not hi- 
therto well understood. T. C. 
TURNPIKE ROADS. 
To the Editor of the Emporium « 
If turnpike roads and their drains, were to be formed at first 
according to the drawings, (See Plate) making the summer road 
to cross the paved road at every change of the surface of the coun- 
try, so as to keep the summer road always on the highest side, 
with a small drain along side of it, (though it may do without any, 
as it has but little water to carry off) and to keep the large drain 
on the lower side, crossing at every change of surface of the coun- 
try, until it can be let entirely off from the road— -In such case, sum- 
mer roads could be kept good at a small expence, as they would 
never be washed with the main body of water. The drains on the 
lower side could be kept from washing, by throwing in stones. 
But where an attempt is made to keep up a summer road 
on both sides, both become drains for the water, and in a short time 
both become inevitably lost ; for a drain makes a bad road. 
It is better to have one good summer road to cross the paved 
road often, than to have none at all. The summer road thus ma*? 
