92 
NATURE 
[May 27, 1886 
operation than a work of art. It is, moreover, an art most 
difficult to communicate. It is only to be acquired by some 
persons, and that after years of toilsome effort, and even the 
most experienced find it impossible to reduce their method to 
any fixed rules or formule. 
CASTINGS AT THE INDIAN AND 
COLONIAL EXHIBITION 
INDIAN 
At the last meeting of the Iron and Steel “Institute Mr. C. 
Purdon Clarke, C.I.E., Keeper of the Indian Section, 
South Kensington Museum, read a paper ‘On Certain De- 
scriptions of Indian Castings” as follows :— 
The importation of partly manufactured material is at present 
exercising considerable influence over many of the native arts of 
Oriental countries and India. The supply of machine-made 
thread has doubled the village hand-looms in some districts of 
Madras, and gold thread from Germany has enabled the brocade 
weavers to compete with the imitation brocades sent in from 
Europe. 
In some handicrafts, however, the supply of European mate- 
rial has produced a contrary effect. Iron and steel, bar and 
rod, have displaced an ancient industry, and sheet copper and 
brass have robbed the founder of half his work. Formerly the 
only means of producing sheet-metal was by hammering cast 
plates, an expensive method, only resorted to when thin flat 
coverings were required for wooden or other objects, For very 
large vessels, where weight was required to be kept down and 
strength maintained, hammered sheet was used; but generally 
the founder was employed, to save as much as possible the 
labour of forming the furnishel castings which required but 
little beating out, trimming, and brazing. 
In the case of a bowl, or flat jar with a narrow mouth, the 
founder would prepare a cast not unlike in shape and thickness 
that of an ordinary flower-pot saucer, from which, by constant 
hammering, the bulbous sides would be formed, projecting 
beyond the rim, which would remain of its first diameter and 
thickness. When finished, such a vessel would be nearly double 
the size of the first cast, and a remarkable example of the native 
knowledge of the composition of bronzes and annealing pro- 
cesses. 
It is worthy of noting that the chief means of detecting 
moder from old Persian and Saracenic metal vessels is by 
examining the brazen joints, which in ancient vessels are rare. 
When not found, a close examination will show the vessel to 
be athin casting, the ornamentation being by inlay, or chasing 
and hammering, which, being done after the cast is made, gives 
the reverse side the appearance of chased sheet metal. 
So far as he could ascertain, there were three methods of 
casting practised in India. The first, by moulds in sand; the 
second, moulds in Clay not unlike plasterers’ piece-moulds ; the 
third, clay moulds formed on a wax model, the etre perdu of 
Europe. 
The first of these was well known in Europe, but the second 
was, he believed, now described for the first time. In preparing 
the mould, impressi ms of the various parts of the pattern are 
taken in clay, and these pieces when nearly dry are, after trim- 
ming, stuck neatly together, and kept in place by several layers 
of mud, in which some fibre is mixed. ‘lhe mould when ready 
has but one vent, which, placed on the most convenient side, is 
carried up into a sort of bottle-neck. If the object is small, 
several moulds are attached together, and the vents united by a 
single short neck of clay, to which a crucible, inclosed in an 
egg-shaped ball of clay, is attached. The size of this crucible 
depends upon the exact amount of metal required to fill the 
mould or moulds; and this quantity being known by experi- 
ence, the founder places it inside before closing up. No pro- 
wision is made for the escape of air from the mould when the 
metal is poured in. The mould and crucible (now in one piece) 
is allowed to dry; and after several coats of clay, tempered 
with fibre, have also been well baked on by the sun, the furnace | 
is prepared. This is simply a circular chamber about 2 feet 
6 inches in diameter, 2 feet in heizht, with a perforated hearth 
and no chimney. Half filled with charcoal, a good heat is 
obtained by the use of several sheepskin bellows from beneath. 
When ready, as many mouldsas the furnace will hold are placed 
in it, the crucible end of each being embedded in the fire. A 
cover is placed over, and the fire kept up until, upon examina- 
tion, the moulds are found to be red hot. ‘They are then taken, 
one at a time, and replaced in a reverse position, the crucibles 
being now above. The metal flows down into a red-hot mould? 
and penetrates the finest portions of the surface without suffering 
from air or chilling. The fire is allowed to gradually cool, and 
when the objects are broken out of their clay covering, the metal 
is soft and malleable. 
The third manner of casting (that by the use of a wax pattern 
which is destroyed in the moulding) was well known, but in one 
particular case the process had been carried further than would 
be at first believed, and of this he would now attempt a 
description. : 
The object produced is an anklet, a flexible ring about 4 
inches in diameter, made from an endless curb chain. Such 
curb chain trinkets are common in India, and are generally made 
from .thick silver wire rings interlinked and soldered one by one. 
In th's example the anklet is of bronze, and consists of a com- 
plicated chain of forty-three detailed links, the whole being 
cast by a single operation. The first part of the process is the 
preparation of a pattern in wax, a delicate work, each link 
having to pass through four others, and to bear three small 
knobs or rosettes. These are in two instances but ornaments ; 
the third, however, serves as a channel for the metal to enter 
each ring. 
Then commences the most difficult part of the work, each ring 
having to be slightly separated, and this is effected by painting 
in a thin coat of fine clay until there is sufficient to form a par- 
tition. Other coats of clay are added until a thickness of about 
half an inch is attained, when a groove is cut round the upper 
side of the ring, and deepened until the row of knobs is bared. 
The wax is then melted out, and the mould attached to a 
crucible as before described. When cast, and the mould broken 
away, the chain comes out inflexible, being attached to a rod 
which runs round where the groove was cut. This is broken off, 
and the chain is complete. 
Having been consulted respecting the trades to be represented 
in the Indian Courts of the Colonial and Indian Exhibition, he 
recommended amongst others a good brassfounder to be sent. 
Dr. Tyler, who was charged with the collection of these 
artisans, engaged one of the best he could find, but up to the 
present the foundry is not in working order. : 
One of these combined crucible moulds was submitted for 
inspection, with fragments of another, also a cast curb chain. 
anklet ; the author concluding by thanking the members for this 
opportunity of publishing an interesting process. 
A NEW SPECTROMETER 
JN equipping the Physical Laboratory of University College, 
Dundee, I felt considerable difficulty in deciding on a 
spectrometer for accurate work ; it was easy to get a simple 
instrument for qualitative experiments and rough quantitative 
work, but dt was only after consulting several friends and com- 
municating with two or three firms that about two years ago I 
wrote to Mr. Hilger, in the hope that from him we might obtain 
an instrument capable of working to as high a degree of accu- 
racy as would enable our best students in the laboratory to do 
advanced work. Considering that a second of are is by no 
means an unusual limit of error in anzular measurement, and 
that it is of the order 1: 1,000,000, the whole circle being unit, 
we thought that while further capability in reading power would 
be more than counterbalanced by various indeterminate errors, 
yet it should be possible to obtain this accuracy with a suitable 
instrument. 
Prof. Liveing was kind enough to give us valuable information 
about one of his own instruments, of which the plans were sent 
to us by Mr. Hilger for inspection; and Mr. Capstick and I 
finally decided to ask Mr. Hilger whether he could not arrange 
two microscopes on the instrument in place of the one which 
Prof. Liveing’s has. 
As a consequence, Mr. Hilger presented suggestions for a 
spectrometer which is now in this college, and is capable of read- 
ing directly to one second of arc and yielding reliable results. Its 
construction is very simple. The collimator stands on a heavy 
pillar by itself; and the circle, divided to five minutes of are on 
a ring 15 inches in diameter, with six radial spokes, is carried 
on another pillar. The telescope, counterpoised, turns on the 
same axis, but does not touch the circle at any point ; and the 
reading is managed as follows: from the telescope-bearing a 
double girder with a semicircular plan tied across its diameter 
by tubes of brass stretches horizontally above the semi-cireum- 
ference of the divided circle ; to this girder are fixed, at its ends, 
