The Sun.
London, England, 1828-03-20 00:00:00

TO THE EDITOR OF THE SUN.

SIR,—In presenting the public with this new pro-
duction, my grand object has been to render thespeak-
ing of French as easy and familiar to English persons,
as if they studied in Paris. To accomplish this great
desideratum, I have composed the essays on the rules
of passages and sentences used in ordinary discourse.
By construing them into French, the pupil will not
only store his mind with useful expressions, but he
will likewise insensibly imbibe just notions of the
Grammatical technicalities of the language. This is
of the utmost importance for speaking French ; for,
unless the learner is properly trained up in the lilac-
tical part, he will never be able to hold the least dis-
course with a native of France, although he may be
a proficient in the theory of the language. The na-
ure of the French Verbs is, also, exhibited in quite,
a new and clear manner, and the remarks on pro-
nunciation are collected from the present practice of
the fashionable circles in Paris. The work is con-
cluded by a Grammatical Analysis, and a Treatise
on French Prosody and Versification; besides a
classified vocabulary, a compendium of familiar
phrases, and numerous models of notes, letters of
compliment and business. In the execution of the
whole, in short, the speaking of the language has a
prominent feature ; and I flatter myself this Gram-
mar will be found peculiarly adapted to the capacity
of the generality of learners, being divided into sixty
easy lessons and essays, which will prove no less
instructive than agreeable.
I have the honour to be, Sir,
Your most obedient humble servant,
London, March 19, 1828. J. V. DOLTVILLE.

P.S. A Key to the Essays is just published.

ECONOMY OF LIGHT.

The following statement exhibits the comparative
expense of an equal quantity of light from different
substances. It is estimated that twenty cubic feet
of coal gas, or ten of oil gas, are equivalent to a
pound of tallow, and five thousand grains of good
spermaceti oil, as equal to seven thousand grains, or
one pound avoirdupois of tallow. Valuing the quan-
tity of light afforded by one pound of tallow in
candles at Is., an equal quantity of light from sperm
oil consumed in an Argand lamp will cost 6d. ; an
equal quantity of light from whale oil gas 4,1 d.; and
an equal quantity of light from coal gas 2,id. This
estimate is made upon the criterion of half a foot of
coal gas per hour being burnt to give a light equi-
valent to one mould candle of six in the pound ; but
when burnt under favourable circumstances, the
quantity of gas consumed does not exceed one-third
of a cubic foot for each candle, and in some experi-
ments not more than one-fourth, which would of
course reduce the expense of gas in proportion.
Mr. Anderson, of Perth, states, that he very care-
fully made a great number of experiments, with a
view to determine the comparative quantity of light
afforded by candles and coal-g,as. The size of the
candles which he employed was short sixes, and he
gives the following table of the.results. The first
column shows the kind of burners; 2d, the number
of cubic inches of gas consumed per hour; 3d, the
number of candles to which the light is equal, as de-
termined by the method of shadows; 4th, the num-
ber of rabic inches per hour, corresponding to the
light of one candle. A cubic foot contains 1,728
inches :

Number of cubic
Kind of Burners. inches of gas
consumed per
hour.
3 Jet
Argand, 5 holes 2,592
Ditto 10 ditto 3,71)9
Ditto 11 ditto 5,940
19+
Ditto 1S ditto 6,804. 21

of can- Number of cubit,
dies giv. inches of gas giv-
ing equal ing light equal
light. to one candle.

346
324
3161
309
324

The mean of these results is, that 323} cubic inches
of coal gas yield light equal to that of one candle
for one hour; but this is the coal gas of Perth, which
he stated to possess a very great illuminating power.
With regard to the superior light of oil gas, the re-
sults of experiments have varied, and of course opi-
nions have been different; but the general conclusion
is, that taking the illuminating power of coal gas as
one, that of oil gas may be stated as from one and a
half to two, varying according to its specific gravity,
which differs from 750 to 1,000; and though coal
gas is generally more uniform in this respect, it varies
according to the quality of the coal and other cir-
cumstances.--Matthews's Compendium of Gas
Lighting.

There was a rumour current amid the circles
of the west end yesterday, though we did not succeed in
tracing it to any accredited source, that it was the inten-
tion of his Grace the Duke of WELLINGTON to proceed im-
mediately to Russia, with a view to confer with the
EMPEROR ma the position of affairs in the East. We do
not at present recollect any instance of such a step being
taken by a Prime Minister ; but the mission of Lord
CasThEßEAcrt, in 1814, if not precisely in point, was at
least analogous. There can be no doubt that the high mili-
tary fame and high civil authority of the Noble Duke would
bestow a weight on his personal advice which no other man
in Europe could attempt to claini,—Morning Paper.