The Sun.
London, England, 1860-09-05 00:00:00

THE GREAT BELL QUESTION.

The Chief Commissioner of Works has, in pur-
suance of a promise he gave to the House of Com-
mons, endeavoured to solve the question as to the
cause of the crack in the great bell of Westmin-
ster, and for this purpose he has consulted a num-
ber of eminent authorities on the subject, among
others, Mr. John Tyndall, F.R.S., Mr. J.
,Mercy,
of the School of Mines ; Professor Airey, and the
makers of the bell, Messrs. Mears. The report was
proceeding just previous to Parliament rising,
but has only been placed in the hands of members
during the last few days.
Mr. Tyndall, one of the referees, after some pre-
liminary observations, on the laws of acoustics,
says :—On the soundbow, and diametrically oppo-
site to the hammer, a number of cavities occur,
forming, a group which is included in a space of 32
inches by 14 inch. The centre of this group (which
is the principal one) is about 121 inches distant
from the edge of the bell. The cavities, six in
number, excepting one or two very small ones, vary
from three-tenths of an inch to less than one-tenth
of an inch in diameter, and the depth of the
deepest of them is two•fifths of an inch. For the
purpose of future reference I will denote the group
by the symbol (G.) To the left of this group (i.e.,
to the left of an observer facing the group), and at
a distance of about 11 inches from it, two cavities
occur, the largest of which measures two-tenths of
an inch across, at the surface, and is two-tenths of
an :inch deep. The diameter of this cavity un-
derneath the surface augments to three-tenths of
an inch. At a distance of a foot further to the left,
and 16 inches from the edge of the bell is a group
of pits, the largest diameter of the largest of them
measuring, at the surface, one-fourth of an inch ;
the depth of this cavity is ono•eighth of an inch.
All the others are small; and with the exception of
one little outlier, the whole group would be
covered by an area of an inch, Between this
group and the point struck by the hammer,
at a distance of four feet nine inches from

the latter, and 14 inches from the edge -Of
the bell, a cavity occurs which measures five-
eighths of an inch across ; it is filled with a foreign
metal, and I am; therefore,unable to state its depth.
At a distance of 10 inches to the right of the group
a cavity occurs one-fourth of an inch in diameter,
and two-tenths of an inch deep. At a distance of
six inches above the latter, and in a line which in-
clines from it to the east, tecavity occurs, measuring,
in its longest direction, one-eighth of an inch at the
surface, but running under the surface until it
attains about three-eighths of an inch in diameter.
Finally, at a distance of three feet four inches to
the right of G, and at 14 inches from the edge of
the bell, a cavity occurs, measuring, in its longest
direction, one-fourth of an inch across, and having
a depth of two-tenths of an inch. All these cavities
appear to have been produced by the rising of air
bubbles through the metal while in a state of
fusion ; and their occurrence along the sonndbow
is, I think, due to the fact that the slope of the
mould at this place formed a kind of roof over the
bubbles and prevented their escape.
Section 3.—On the Cracks in the Bell.—The

principal cracks are two in number; the first, which
I will call C 1, is diametrically opposite to the ham-
mer, and hence in the middle of a vibrating seg-
ment. It is nine inches long, and runs transverse
to the soundbow. It does not reach the edge of
the bell, but terminates two inches above the edge.
The second crack, C 2, occurs at a distance of two
feet four inches to the left of C 1. It also runs
transverse to the soundbow, measures 13 inches in
length, and terminates at a distance of five inches
from the edge of the bell. This crack occurs within
15 inches of a node, and the amplitude of the vibra-
tions immediately adjacent to the crack was found
by experiment to be less than that of the vibrations
at the node itself. Besides these two principal
cracks there are three minor ones, varying from two
and a quarter to two inches in length. Were the
hell closely examined with a good light, additional
small cracks might possibly be detected. To the
naked eye the sides of the cracks appear to be in
mechanical contact ; but when a wet cloth is
dabbed against the larger ones, the water is forced
into them, or soaks in by capillary attraction; and
when the boll is struck, subsequently, bubbles issue
from the cracks throughout their entire length.
Section 4.-00 the Connexion of the Cracks and
Cavities.—The pits above described, and other
smaller ones which have been disclosed by. the
removal of a portion of one of the ornamental rings
of the tell, must undoubtedly be regarded as de-
fects; bst how far such defects are unavoidable in
the casting of large bells I am not in a position to
state. My duty at present is to estimate the
possible influence of the cavities in the production
of the cracks.

The first principal crack, C 1, certainly originates
(or terminates) among the lower members of the
group of cavities denoted by G 1. Two of the
lowest holes, both of them small ones, are about
three-fourths of an inch apart, and occur nearly in
the same vertical line. The crack commences mid-
way between. both, intersects the lower cavity, and
afterwards passes through an impitted portion of
'the bell. Hence, though the superior end of this
crack is close to the cavities of the group G 1, the
fact that it reaches less than half an inch higher
than the lowest member of the group, and that the
main body of the group is. not,- intersected by the
crack, tends, in my -opinion, to invalidate the as-
sumption that this crack has been caused by the
cavities. But setting this apparently doubtful-case
aside, a reference to the other cracks appears to me
quite fatal to the notion that the cracks are due to
the cavities. The second principal crack, denoted
by the symbol 0 2, is the most formidable of all,
and it runs from beginning to end through an im-
portien or the metal. As for the minor
cracks, no cavity occurs near to any one of them..
With regard to the manner in wlich the bell is,
suspended, I do not think that it had any influence
in the cracks. Thus, I think the elements
of the question reduce themselves to two, viz,, the