The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1851-05-13

consistent with diametric FORM il probable that the
crystals modified oblique prisms.
Some specimens from different localities dark
colored that Is impossible to give them Satisfactory
animation; and list Of such i given As however the
mic examined from Greenwood and Sesuv!us baxi
a. it is probable that all micas with similar chemical
constitution also and is doubtful whether there are
any which can be considered uniax il.
After which, the Association took until eight
o'clock this evening.
THIRD DAY
WEDNESDAY, May 7, 1853 A. M.
The first paper read, this morning, was on the
Special Homologies Of Acephalis, by l.. Agassiz,
Of Harvard.
]. p. KInrLAsD, NJ d., road an intere sting paper
on the Sexes and Habits ofsome ofthe Acephalous
Biyalye Mollusca.
A. d. BAcnE, Superintendent Of the Unitei
States Coast Survey, addressed the Association re-
latiye to comparison Of curves, showing the
dephia, Toronto and Hobart Town."
Prof. BACHE explained the nature Of the obser..
yations made at the magnetic obseryatories, and
the provisions for reducing and publishing them,
which are now in action with the most saisfa story
results. Any theory Of changes in the magnetic
declination now proposed, must stand the test Of
numbers; it must include quantity as we'll as direc-
ton, to be worthy Of consideration. To this point,
these observations, extended on the globe, have
brought the subject The several diagrams should
be the average hourly changes Of the magnetic va
ration, during the day at Toronto, Hobart Town
and Philadelphia. They were for the FIVE months
when the sun is north Of the equator, for
the FIVE when it is south, and separately for the
two months, during which the sun Is in part north
and in part south Of the equator. The sources
from which the diagrams were taken, were stated.
The curves for Toronto and Philadelphia present
a remarkable accordance in times OF ma ximum and
minimum, and in the motion Of the needle between
the times, the slight difference being in part appa-
rent only, and resulting from the fact that the OBJ
seIvations at Toronto were pade hourly, and those
at Philadelphia biheurly. AL the conclusions in
regard TO the effect Of seasons, ara the IKE, wnicn
have been drawn by Col Sabine from the Tors' ep-
ssryatons, are deducible from those Philadelphia
The relation OF the mo lions Of the needle at Ho-
bart Town. in south latitude nearly the same AZ the
north latitude of Philadelphia, was pointed out
From the publication Of the very extensive and
valuable series of combined observations which are
now, in part in the hands of scientific men for dis
cussion md comparison, the most important results
may be ANTICIPATED.
The next paper In order, was
On a new method Of geometrically contracting
read by Professor PIERCE, Of Harvard.
The followirg'is an abstract Of this paper
The spirit Of this method consists in con structing
the arc Of the curve from its radius Of curvature,
which represents ts derential coeflccnt, provided
the variable represented by the angle which the
radius makes with fixed axis. The function % be
in'egrated, must be regarded rs the Of another
curve which is not, however required TO be actual
~ drawn; but substitute for it may be found in
isoperimetrical polygon. which may have many
sides aswe lease TO give ii, This pclygon is TO be
taken the in, olute Of the required curve which
represents the integral, and this method is espe-
cially adapted to the Indignation OF trigonometrc
functions.
Prof PIircr rcmarked that Mr.. HIS method
may be showntc have simple and neat CORE
spondonce with the analytical method Of quadra-
lures adopted by the best geometers and especially
With those adopted n the perturbatons Of the Aste
r0ids. IL may also be made 10 illustrate some Of
the most rccondite ofthe problems which occur in 4
planetary perurbations, and especially what relates
he odd ion. uf Ion,
JA1r> HArL, Palrcntologist Of the Lake Supe-
ror Land survey. resd paper on the Siiurian
rock- Of that district.
A curious fact in relation 10 the Turbine Wheel,
by Mr.. J. Chace, If Msss.-This paper wa read
by Prof Pefee, G! lIalrard aud the following Is AN
@.| .t
In computir the experiments which were made
al Lowell in the present year BY Mr.. Francis, IL
was found that when the gate was fully open. tho
quantity of water discharged through the guides
Nas 20 per cent Of the theoretical discharge. The
effect Of the wheel during these experiments was
II per cent 81 the power expe bdca but VIII, the
gate was half open the eject was ~ per cent Of
the power, while tho discharge through the guides
wa u per cent more than the theoretical dis.
charge but when the opening q the gate WAS
still further rciuc. Ia one fourth &C the full openng
tie effect was also reduced to IS per cent of the
Ioecr, while the discharging velocity was raised to
" Per cent more ,han tia! given BY theory In
The first 81 these experiments the fall wns " : 20
feet. ire second Is 2-lp feet, and in tie third
~ 5lGO feet and the quantity &C water used upon
the wheel Within full gate vac l35 cubic feet per
second.
Prof PrircE remarked that Il 10 The las, Of these
experiments the wheel were removed and he water
suffered to run through the guides without obstruc
ton, the head, which would b. required 90 gi,c
velocity 1t discharge equal TO that actually obscrv-
ed, would be about 3sA feet.
Prof j. HENRY, Of the Smithsonian Institution,
read paper ION IA apparatus for determining alt
tudes by means OF the boiling point.
Prof GEorcE Coski.Ey, Of -. James, addressed
the Association. "on thc motion ~ The sun about
The centre Of gravity of the Solar system"
Prof PEiF.h, of Harvard. then read paper con
Curve for Railroad tracks" of which the fol-
lowing Is an hbstract:-
This papcr recommends n civil engineers two
curves for unequal tangcnts, in which the degree
or DETECTION increases BY equal increments, and
which are thus cadiy laid down as usual with the
The odolite and chain. But without diag grams and
iomulr, II does not admit Of ineligible illusra-
ration.
After which the Association took a recess un.il
three o'clock, l.. NJ
AFTERNOON SESSION
After an hour spent in the examination of geolo-
gical specimens, pronounced by Professor Agassiz
to be the finest collection he had seen in this coun-
try, in Europe, the Association came to order,
aud listened to the report of the committee ppoiht-
ed at the New Haven meeting upon Professor
Nlitchcl's System Of Astronomical Observations.
The report was made by PEIRcE, Of Harvard,
and Is 20 interesting in itself and has been looked
forward to with 80 much interest BY tho ssvans Of
this country and Of Europe, that send IL to the
Herald in full. II is ss follows
The committee appointed for the examination Of
Professor Mitehcls method of observing right as
tensions and destinations by the aid Of magnetism,
report in part
They have made preliminary examination Of
Professor NitchePs apparatus, and Of his books
Of observations Everything has been freely open
cd to rigid scrutiny, which has been sought
earnestly by the Astronomer himself; and they
have felt II to be their duty to investigate every
reasonable, and even every possible source OF doubt
and error, with patience and fidelity. They would
harc nreerred Ali aXnrcssiQn If amman