The Sun.
London, England, 1830-03-25 00:00:00

LONDON, THURSDAY EVENING, MARCH 25, 1830.

In a few days will be published, in 3 vols. post Bvo.
THE KING'S OWN.
A Tale of the Sea.

By the Author of the " Naval Officer."
Henry Colburn and Richard Bentley, 8, New Burling-
ton-street.

Just ready, in 2 vols. post Svo.
E R T •It U 1) E.
A Tale of the Reign of Henry IV.
" Oh Love! what is it in this world of ours
Which makes it fatal to be loved ?—Ah ! why
With cypress branches hast thou wreathed thy bowers,
And made thy best interpreter a sigh ?"-13Yitox.
Henry Colburn and Richard Bentley, 8, New Burling-
ton-street.

PARLIAMENTARY PAPERS.

CORN.

An Account of the Quantity of Corn, Meal, and Flour,
Exported from Ireland to Great Britain, from Jan. 5,
1828, to Jan. 5, 1830.

Years en,

led Jan. 5.

1830.

Quarters.
97,140
10,444
2,011
1,417,729
4,435
569
310,084

PRICE 7D.

MR. GURNEY'S STEAM-CARRIAGE.

MR.L
0 lENRGA PTAOT HTal
naHdtHEe
rIAnyEoSbrDe:ADDRESSED
H:
EintTdh
eHTI FEwnce wosia.Lt
h.-
someSIR, gentlemen Having,
lace, of Greenock, near Glasgow, respecting some
points in the application, &c., of Mr. Gurney's car-
riage to common roads, I have been solicited to make
my reply through your columns, as the best means
of giving it the most extensive publicity.
In your Paper of September 8, I entered into a
pretty full description of Mr. Gurney's invention,
which in a pamphlet afterwards addressed:to the Duke
of Wellington, was still further extended by a mathe-
matical development of the theory of its action.
This pamphlet contains many things which it would
be impossible to discuss in a newspaper. Leaving
these, therefore, to the more inquisitive of your
readers, I shall merely touch on such as are more
intimately connected with the inquiries of Mr. Wal-
lace, for the information of the public and the United
Steam-Carriage Association.
Generally, whatever roads are good for stage-
coaches are equally good for steam-carriages. Hard
level roads are, however, of the first importance. If
we consider that the traction is doubled in ascending
a hill rising one foot in twelve, and trebled in a hill
of one in about six, we shall immediately perceive
the advantages of levelness of road. Probably a
steamer would take double the load, or the same
load double the distance, in the same time, on a level,
that it would up a hill of one foot rise in 12; and in
the case of a hill changing its level one foot in six,
these doubles would, I presume, become trebles. In
all new lines of road, therefore, we should bear in
mind this circumstance, that a trifling increase of
distance is of much less consequence both in time
and load than hills.
No one will, I hope, imagine that I mean for a
moment to impugn the ability of steam-carriages to
ascend any hills that we have. The contrary I have
pretty amply shown in the pamphlet before-men-
tioned. I merely intend to impress on the con-
structors of new roads, that it would be far more
economical to expend the powers of steam on a level.
though the distance be somewhat greater, than in
the climbing of hills. Another argument is the
comparatively trifling wear of roads by steam-
coaches; so that a little extent of road sinks into
insignificance. By my computations, the wear of
the roads by stages and their horses, duty for duty,
is at least sevenfold that of steam-carriages.
Nothing certain has come to my knowledge of
the cost of these machines ; but I apprehend from
4001. to 6001. will not be far from the limits of ex-
pence for one—a sum which, when we reflect it is
for an instrument that in perpetual use on a level
would do the work of 200 stage-horses, will appear
a mere bagatelle. The expence on the road for
fuel is only from 2d. to 4d. per mile; hut, including
wear and tear, men, duty, turnpikes, &c. will, from
the best data I can procure, be about a third that of
stage-coaches. Probably the expences in the out-
side will not enable the proprietors to run for less
than half fares. After, however, they shall have
established their stations, pumps, &c., I have no
doubt they may with equal benefit to themselves do
it for a third, or possibly a fourth of the rates in the
present mode of travelling.
Mr. Wallace is anxious I should give an opinion
of the speed of these carriages. For my part I can
see no limit to any rate which the materials could
stand. A steamer might, in my opinion, be con-
structed to run on a common road 50 miles per hour,
or more if required. In the trial before the Duke
of Wellington, as stated in a former letter, I rode
with Mr. Gurney over a ground that had been mea-
sured at an average rate of nearly 17 miles per hour;
and where we had no interruption at between 20
and 30. A horse of the 10th Hussars, which ac-
companied us, and which I was informed could trot
at the rate of 16 miles per hour, was often obliged
to gallop with no inconsiderable exertion. This
was over a large gravelly soil, particularly unfavour-
able to the experiment. A similar circumstance oc-
curred in the journey to Bath. I was assured that
some post horses were in a short time "so blown,"
as to be incapable, unless with the utmost difficulty,
though they had nothing after them, to keep up
with the carriage.
We may take it for a general rule, that the power
and speed of the carriage will depend on the quan-
tity of steam generated ; and this again on the
strength of the fire and quantity of surface in the
boiler exposed to the fire. It may also be added as
a consequence of this, that the load and speed are
reciprocally proportional,—the greater the one, the
less of course will be the other. Up hill, therefore,
the apparent load being greater, the speed must ne-
cessarily be less, if some artificial means be not re-
sorted to of increasing the quantity of steam. Here
Mr. Gurney's skill appears to considerable advan•
tage. Without the method he has adopted the
carriage would nearly be useless. After the steam
has done all one would think a reasonable man could
expect of it in propelling the carriage, Mr. Gurney's
ingenuity exacts a parting benefit in the way of
blowing the fire for the production of more. This
singular extortion of service is productive of the
happiest effects; for it gives him almost unlimited
control over the fire, and of course over the genera-
tion of the steam and the power of the carriage.
Much doubt has arisen respecting the manageabi-
lity of Carriages of this sort. Personal observation
has proved to me that they are much more readily
stopped, more accurately driven, arid more easily
turned, and on considerably less ground, than any
stage-coach can possibly be. Paradoxical as it may
appear, the guiding apparatus is incomparably more
obedient when the carriage is in motion, though
over rough ground, than when still and on a boarded
floor.
Connected with this is a fact yet more extraordi-
nary. For instance, when the contrivance for in-
creasing the bite of the wheels is applied, the car-
riage's power, supposing we have a sufficieney of
steam, always increases in proportion to the load,
and the difficulty of drawing it. And when the
carriage is so constructed as to be capable of draw-
ing the greatest weight up the steepest hill, it
would, unloaded, be unable to move itself alone on
a level. This is demonstrated in the pamphlet al-
ready alluded to. •
From the mathematico-experimental principles of
carriages on common roads, there is a uniform re-
sistance, which, estimated for a second, I find
amounts to nearly two miles per hour. This re-
sistance is that which the propelling power, what-
ever it may be, has to overcome; and it is the same
for every velocity. Now were this alone to act, a
carriage moving 10 miles an hour would be reduced
to rest in five seconds, or when it had run only 12
yards; and if moving 20 miles per hour, in 10
seconds, or when it had gone but 49 yards. Thus
merely t con tt
arrestittg the
off the steam
progress w ooufl generallydaste,l
m er within be
suf-
ficient
limits, I presume, less than those in which any
coach with horses at the same speed s
c,
could " pull
shoe-
drags,"up" But
he by
carriage
stopped, at whatever
rate it may be going, almost instantaneously.
t the help
may o
bef Mr. Gurney
It is owing to this uniform resistance that there is
a considerable economy in speed. I have been in-
formed that 100 per cent. in velocity is acquired at
an expense of only 17 or 20 per cent. in fuel.
Whether this be a correct estimate or not, I am un-
able at present to say; but I have some views
which, should,l have leisure to pursue them, will, I

have-no doubt; lead to a.tolerable approximation.
Meanwhile we may observe, that were the expence
of fuel, instead of 17 or 20 per cent., to amount to
100 per cent. for a double velocity, the advantage
would be incalculable on the side of steam-carriages;
for it seems, with horses, the expence of maintain-
ing nine miles per hour is double that of maintaining
seven; and at higher rates, of speed the expence in-
creases enormously.
Before I quit this part of the subjeet I cannot
resist calling the attention of men of science to a
law which I believe to be new. If, however, it be
not, it had never come under my notice, and I shall
feel thankful to be corrected. From the experiments
at the Hounslow barracks, it appears that the bite
or hold of the wheels on the road is s.6ths of the
weight on them, and the force of traction a 1-12t1o,
making the former ten times the latter. It is like-
wise stated, that the experiments with the Novelty
on the rail-road gave a tractive force of 91b. to the
ton, or 1-249th of the load; and that it drew nearly
ten times its own weight. If so, the bite must in
this case, too, be between ten and eleven times the
force of traction. From the near agreement of these
numbers on bottoms so very differently constituted
as a railway and a road worse than very indifferent
turnpike, and with weights varying from five to near
forty tons, one would infer it holds good generally.
Should future experiments confirm this inference, it
will not be an unimportant addition to our know-
ledge in the theory and practical application of loco-
motive machinery.
I have been long anxious to offer a few observa-
tions on the beneficial effects likely to result to the
agricultural and other collateral interests, from the
introduction of steam-cariages, and their probable
application to the purposes of agriculture; but other
engagements have so interfered, that I am obliged at
present to lay them aside.
I am, Sir, your obedient Servant,
Cranford, March, 1880. JOHN HkRAPATH.

P.S. The public, I find, is 'desirous to know
when these-long-expected carriages are to appear.
At present Mr. Gurney is in Wales, whither he very
unexpectedly went, at the request of a large iron
proprietor to make experiments with the carriage
en his raillways ; but I am assured preparations are
making to start some of them in the neighbourhood
of London as soon as he returns. As I said in my
last, whatever information I get on this subject I
shall communicate to you, to lay it, if you think pro-
per, before your readers.