The New York herald., 1851-08-29

He instanoed three modes in which mech anicai
force might be employed, viz: 20 com municats mo.
tion in body free to move (ss when one ball
strikes another at rest); to overcome fixed obsts.
Gle (as, for example, to break an inhexible bar,
to produce a pressure); and, to penetrate spa 20
when opposed by some retarding influence. Wnen
employed in the first of these modes, he remarked,
tie "work done was generally admitted to be pro-
portional to the velocity simply, and not to its
square. He mentioned single experiment which
had been supposed to prove the contrary, wilt
that four similar elastic springs will impel body
with only double the velocity that one will do; but
he showed that this experiment, when properly OK.
planned, was in harmony with the law.
To prove that in the second use, where for,e was
employed to produce pressure, it varied as the veo
city simply, and not as its square, he referred 10 the
experiments and table of Mr.. Rouse, on the relar
tion between the force and velocity of winds, and
showed that his results argued much more nearly
with the former hypothesis th an with the latter.
He showed that most of the experiments which
had been adduced in support of the doctrine he was
opposing, such as the firing of nusket bal into
log, or through series OF parallel homogeneous
plates, the grinding Of grain, &c resolved them
selves into cases of retarded motion, in which 1t is
well known that, if the retardation is uniform, the
space varies at the square OF the velocity; but he
objected to using space only, without reference to
the time in which it is described as true measure
OF forcefrst, because its results were at varan 20
with those obtained by the other two methods,
which equally phoso phical and worthy of Gre.
dit; second, because it was not simple, inasmuoh
it unnecessarily introduced new and uncertain ee.
meDt into the account, viz the medium or inhu-
ence which retards the motion, which might, in
deed be uniform, but which might alss vary ac-
cordipg to any law, or to no Law at all. The OK.
paDsive force of the gunpowder, when cannon
is discharged, might be measured, he remarked.
by the velocity given to the ball, or by the
pressure against the sides and breach of the
gun, and all is simple, and we should have har-
monious results bat If attempt to measure it by
the distance to which the ball il thrown, We must
take into account all the various resistances that
the ball will have to encounter, and which may be
very irregular in their operation. He objected to
it. thirdly, because it omitted the Important ele-
ment oftime. If one force does four times as much
woik as another, but employs double time TO do
it in, it is really but twice rs great; so that in
all such cases we must divide the work done by the
time in which it is done in order to obtain the true
measur re Of the force. If this done the ex-
perments quoted 10y his opponents, he remarked,
that the results would, in every case. be proper
tional to the velocity simply in the other
NEW FORM OF MICROSCOPE, WITH IMPROVED ME-
THoDs OF MEASURING THE DIMENSIONS OF OBJECTS
AND THE ANGLES OF CRYsTALS-BY PROFESSOR ].
LAWRENCE SMITH. (ABsTRACT)
The construction of this microscope is based upon
the principle OF placing the objective glasses be-
meath insteai of above the objects to be exa mined
The tube in which the eyegass is, is thereby five
degreesfrom the perpendicular, and the ray of light
undeIgoes detection of one hundred and forty de-
grees before entering the eye. The Detection is
produced by a four sided prism, with the angles
55 deg, 1913 deg, 52a deg, l45 deg, the ray Of
light passing through the objective glass down;
subjected to two total reflections, and pass out Of
the fourth surface upwards, making an angle Of
thirty-hve degrees with the perpendicular. The
eye regards almost at the same moment the object
ITSELF the stage Of the microscope, and the image
Of the same in the instruments and here the advan-
tage Of the instrument is seen for chemical pur-
poses, for which it was originally intended 1t is,
however, not confined TO this, for owing to the
convenience it affords for arranging the illumi-
natiop, it is well adapted to much general use. The
new plan of measurement is to induce a microme-
ter into the tube Of the microscope at any stage of
the observations, by means Of arrangement
placed so that the mcrometer comes within the
plane of the foci of all the e-pieces used the
Instrument. The me thod Of measuring the angles
Of crystals is by having grad uated cir,e in the
outer part Of the tube of the microscope, and pass
ing from the tube carrying the eye. pieces, which
has circular movement independent of that Of
the graduated circle. The manner of measuring
the angles is follows Introduce the microme-
ter, turn the eye piece until the lines on tAe mi
crometer parallel to one side of the angle to be
measured; then, leaving the eye-piece, turn the
gradua ted circle until the index on the eye piece
at zero; this done turn the eye piece until the lines
on the microme,er parallel with the other side
Of the angle to be m assured, and in regarding the
circle, the degrees Of the angle passed through will
be seen. The method is convenient, and more pre-
else than any known.
on NEW LOCALITY OF RED SAPPHIRE, WITH NO
TIcEs TIE ASSOCIATE MINERALs-BY wM. p.
ELAKE, OF YALE LABORATORY. (ABsrRAcr)
These crystals of colunuuln remarkable for
their great irIegularity Of form and outline, beiog
almost without exce pton, filed with cavities,
to present. meie shell of solid sapphire The color
OF the finest specimens Is ruby red passing into va
rous shades Of purple in dilerent speci mems They
are translucent to opaque; no transparent speci-
mems have yet been founi
The associate minerals are remarkable for their
beauty and peculiari,ies. The following list en-
braces those which occur in greatest abundance; -
Red spinel, rose spine, hydrous silica of alumaa,
chondrodite hornbende iron pyrtes, hydrous ses-
qui oxide OF iron, graphite, phog-pite, emerylite.
The following occur sparingly -Rutie, ilmenite,
blue fuor.
1t is interes sting to observe the similarity of the
association Of the minerals Of this locality with
those described by ProfessorJ ]. Liwrn;e Smith, 10
bis Memoirs upon the CoIundum aud Survey Of Asia
Minor, read before the Academy of Science of the
French Institute, July 10, 1850, and published in
the American Journal Of Science.
Mr. Blake presented a commune alton upon
some American minerals, stating that he had oh
served the occurrence OF ehromate of lead In Penn-
syivania, upon pyromorphte and carbonate Of lead.
lie also noticed the occurrence OF chacotrciuto ut
PefkromeDnime, Penngy sulphuret of neckel,
Lancaster county, Pennsy lvania; zenite, from
ONiel Mine, Orange county, New York.
on THE ALTERATIONS or MARINE AND TERRESTRIAL
oKGAN1c REMAINS IN rae cARBoSIFERoUs SYSTEM
OF ONO; TY J. W. FOSTER.
Mr.. FOSTER, Of the u ). G Survey, described
a section of the caTbunferous rocks of Ohio, in
which 10 less than ten aliimatIons OF marine and
terrestrial organic remains occur in vertical
range Of about 500 feet. The terrestrial remains
CONSISTED of plants belonging to the genera Lspi-
dodendra Sigiilevria. Nenoptevis, Sc, while the
marine deposits contained opcriterl Proddc,s, Co
nIattes ana Chonetes. lie alse spoke Of the os-
currebce of two genera OF fossil fishes, tho one,
coIoinR to Agasslz, belonging to Petsloius, allied
to The Port Jackson shark the other neco.ypc in
termed uiate between Cieuacanthus, Gyraola IA thus
and lly bodus This is the irst instance observed
Of the occurrence of these remains in the carboni-
ferrous Of the United states
ANALYSIS OF ESDIvE (CtCHoRIuN EvDIvA)-Br j. IL.
SALISBURY, NJ. %.
This plant is ba.dy aunual, q naive Of China
and Japan. The samples analysed scre large and
sGcoulent Average length Of tops eleven inches.
Average weight OF each plant SIX ounces.
Pu otnioge u vGtr, Dry Hsit,, anf Inorganic
Ngttu
Per centsge Of water ......................9 92j
Dry matter. S.uI5
inOrg lnic mat er ............ IUl0
inorganic tla gterin d y matter IL J07
will be seen tnat this plant Is highly charged
with moisture. The fresh tops contain but about