In the early part of the year 1849, I had formed an intimate
acquaintance with a Mr. Cromartie, a Jamaica sugar-planter, and at many
of our friendly meetings we had discussed the question of the sugar
manufacture as then carried on in the West Indian Islands. The more I
heard of the state of this important industry, the more astonished I
became on finding out how rude, how unmechanical, and how unscientific
were many of the processes then employed, not only in extracting the
saccharine juices of the cane, but also in its after-treatment. By a
curious coincidence, at this very period the imperfection of the
Colonial sugar manufacture had attracted the attention of the Society
of Arts, and his Royal Highness Prince Albert had taken a very special
interest in this subject, and generously offered a gold medal to be
awarded to the person who should, during the ensuing year, effect the
greatest improvement in the mode of expressing the saccharine juice of
the sugar cane. I was much interested on hearing this, and applied
myself to the problem with great zest, for I heard that the contest
was to be an unusually sharp one. I was informed that the manufacturers
of Colonial sugar machinery looked on it as a question that would
decide which firm was in future to do the bulk of the Colonial
engineering work, and that powerful vested interests were supposed to
be at stake. This rendered it the more necessary that I should make
every effort to gain such a knowledge of the subject as would enable me
to devise a machine capable of extracting, as completely as possible,
the whole of the juice from the cane. I, therefore, in the first
place, obtained from Madeira a bundle of sugar canes, and I may say
that up to that time I had never seen a cane. Those I had ordered to be
sent to London arrived fresh and full of juice, as
I had directed that their ends should be dipped in melted pitch, so as
to prevent decay, and the escape of any juice from them.
These canes were from 1 1/2 in. to 1 3/4 in. in diameter, having
dividing knots at from 5 in. to 7 in. apart, throughout their length.
The cane consists of an outer tubular part of hard fibrous wood, thinly
coated with very hard pure silica; the interior of the thin wooden tube
is filled with a soft pithy matter, almost like a sponge, saturated
with juice, of which the ripe mature cane contains about 88 to 90 per
cent. of its whole weight. I put short lengths of these canes to many
tests in different ways, and especially noted their great elasticity; a
6-in. length, suddenly pressed between two flat surfaces, would lie in
a complete pool of juice, and if the pressure were quickly released,
the flattened elastic tube would again expand and as quickly reabsorb a
very large portion of the fluid with which it was in contact. Here, I
saw at a glance, was the weak point in the roller-mill, in which the
cane quickly enters between a pair of rolls, and is for the moment
collapsed. But as it emerges from them it again expands by its
elasticity, drawing into the expanding spongy mass a large portion of
the juice, which is
rapidly flowing in contact with it, over the lower roll of the mill.
This will be readily understood by reference to the engraving, Fig. 17,
page 87, showing in section a pair of iron rolls A, A, between which a
cane B is passing in the direction shown by arrows. It will be
observed that at the central part the cane is crushed very thin; but as
it emerges, it, in part, recovers its former dimensions, and in doing
so absorbs a very large percentage of the juice previously expressed.
These and other observations, carefully made and noted at the time,
forced on my mind the conviction that no form of roller-mill could,
from the inherent nature of its action, give satisfactory results; and
that a slower and longer continued pressure on the cane must be
resorted to, if the greater part of this valuable fluid was to be
extracted.
By means of the hydraulic press, 86 per cent. of juice could be
obtained; but this system was far too slow, and entailed so much labour
as to render it impossible to deal with the enormous mass of canes
grown on a moderate-sized plantation. Following, however, the general
idea of the press, I designed an entirely novel system of extracting
juice from canes, the main feature of which was the cutting of the cane
into lengths of about 6 in., thus leaving both ends of these short
pieces open for the escape of the juice, instead of operating in the
usual way upon canes of 4 ft. to 6 ft. in length, having numerous
transverse knots or partitions, which effectually prevented any escape
of the juice endwise. The two convex surfaces of a pair of rolls of 2
ft. in diameter, pressed on less than 6 in. of cane, at any moment, and
if they revolved as slowly as five revolutions per minute, the 6 in. of
cane passing between them commenced and finished the period of pressure
in just one second. In the cane press about to be described, every one
of these open-ended 6 in. lengths would be subjected to intense
pressure for a period of two and a-half minutes; in practice, it has
been found that the juice was vigorously given out for the first
minute, and then gradually declined; finally ceasing to yield one drop
more of juice for about half a minute before it was discharged from the
open end of the press tube.
In order that this new system of continuous pressure might be fairly
tested, I erected a complete press and steam engine combined, at my
experimental premises at Baxter House. I also imported a large quantity
of canes from Madeira and from Demerara, for the purpose of studying
their structure, and making experiments with them, under varying
conditions of pressure and time. The quantity of juice which this small
apparatus was found capable of expressing exceeded 600 gallons per
hour. The juice was much more free from pithy fragments than that which
was obtained from the roller-mill, while the quantity of colouring
matter and chlorophyl extracted from the knots was much smaller,
because in the press these hard knots sank into the softer surrounding
parts, while between the rolls they got far more pressure than the
softer parts of the cane, because of their greater solidity. But the
most important result, which was fully established, was the high
percentage of juice obtained.
In our first experiment, made immediately after the arrival of the
canes, the quantity of juice obtained exceeded 80 per cent.; in another
experimental trial, when the canes had been four months cut, 73 3/4 per
cent. was expressed; and, later on, in a public experiment, when the
canes had suffered from drying, 65 1/2 per cent. was expressed. In
reference to the far smaller quantity of juice obtained in practice by
the old system of rolling-mills, I may quote from the Seventh Report of
the Parliamentary Committee on Sugar and Coffee Planting, where, at
page 259, will be found a memorandum dated "Colonial Laboratory,
Georgetown, 3rd February, 1848," from Dr. John Shier, Agricultural
Chemist, who -- speaking on Sugar Mills -- says:
From numerous trials on various estates, I am satisfied that the
average yield does not exceed 45 per cent.; the first of all
improvements then seems to be to obtain a larger percentage of juice
from the cane.
It is a curious fact that throughout this competition no one but myself
came forward with any plans to do away with the roller-mill. There were
plenty of improvements in this class of machine; two rollers and three
rollers, new gearing, and combined engines and mills. In one case a
magnificent mill had been patented. It was a combined engine and mill,
weighing no less than forty tons -- no light matter to pass over
half-made Colonial roads -- and it was designed by Messrs. Robinson and
Russell, who were large sugar-mill manufactures in London.
The extreme lightness of my cane press formed a strong, and from a
Colonial point of view, a most important, contrast to this. The press
was put to work, and publicly exhibited to dozens of persons who were
owners of sugar plantations in our various sugar-growing Colonies, and
great expectations were formed by them. They saw the canes weighed and
operated upon, then the squeezed mass again weighed, the reduction in
weight clearly showing the quantity or percentage of juice obtained by
the press, which was admittedly at least 20 per cent. more than the
average produced by the old roller-mills then universally employed. The
juice obtained was very rich in quality, in consequence of a
considerable evaporation from the canes which had gone on during the
three or four months since they were first cut. As a matter of
curiosity, I manufactured from the juice obtained about half a
hundredweight of crystallised sugar of very good quality, which I
presume was the first sugar ever produced direct from the sugar-cane
in London, and was much prized as a matter of interest by some of my
friends for that reason.
Without going into the minutiae of detail, it may be interesting to
give a short description of the cane press, which is here illustrated
by engravings copied from drawings of the press, as erected at my
experimental works, Baxter House.
The first engraving, Fig. 18, on Plate VIII, shows a side elevation of
the press, and the steam-engine with which it was combined, on one
large bed-plate.
The second engraving, Fig. 19, on page 91, shows a
vertical section through one of the gun-metal perforated pressing
tubes; the interior of these was of rectangular form in cross-section,
being 6 in. in height by 3 1/2 in. wide.
In the centre of each of these tubes there was a massive plunger
fitting accurately. A square steel bar passed through the two plungers,
and also through slots made in the sides of the tubes for that purpose,
the outer ends of these bars being rounded and fitted into the ends of
two massive connecting-rods, which were actuated by a pair of
short throw cranks formed one on each side of the central crank of the
steam-engine. This arrangement is best seen in Fig. 20, page 91, which
is a plan of the cane press and engine.
From the upper surface of each of the pressing-tubes, two tall circular
hoppers stood vertically, and were attached at their upper ends to a
stage or floor on which the canes were delivered, and where two
attendants were stationed, whose business it was to continually drop
canes into these tubular hoppers. When the several parts of the
apparatus were in the position shown in Fig. 19, page 91, the plunger
had cut a 6-in. length off the lower ends of the canes in the left-hand
hopper, and had pushed them against the compressed mass of canes
occupying that end of the pressing tube, the result being that this
mass was moved a little way further along, the fluid parts escaping
from the numerous perforations in the tube.
While this had been going on the canes in the right-hand hopper had
fallen down into the pressing tube, and the return stroke of the
plunger would then cut off a 6-in. length from these canes, and force
them up against the mass of canes occupying the right-hand end of the
press tube, moving the mass of flattened canes a small distance
forward, and discharging a portion of them from the open end of the
tube. In this way every rotation of the crank cut off portions of the
canes in each of the hoppers, and carried then forward, thus keeping
the tubes always filled with a mass of compressed canes, which were
jammed so tightly in the tubes as to offer an immense resistance to the
plunger, governed by the length of the tube. The two cranks which
actuated the plungers were at right angles to the crank operated on by
the steam power; hence, when the engine was exerting its greatest
power, the cranks actuating the plungers were passing their dead points
and thus exerted an enormous force on the mass of canes, which moved
forward but a very small distance at each stroke.
With the engine running at only 60 strokes per minute, each plunger cut
off two 6-in. lengths from each cane in the hoppers; and as there were
four hoppers with two canes in each, 4 ft. of cane were operated upon
at each revolution, or at 60 strokes per minute only, some 240ft. of
cane were cut and pressed per minute. It was found that the canes thus
passing along the tubes were forced out of the open ends of the latter
adhering together, and looking like a polished square bar of wood; the
juice of the cane passing through the numerous perforations and
falling into the square cistern formed beneath then by the massive
bedplate, was conveyed away by a pipe to the evaporating pans.
The committee appointed to judge of the various plans submitted in
competition for the gold medal offered by his Royal Highness, Prince
Albert, came in force to Baxter House, and witnessed the cane press in
operation. Although the committee did not openly express their views
to me, I could not doubt that their convictions were entirely in my
favour, a natural result of the incontrovertible facts I had placed
before them. In due course I received a notice that the prize so much
coveted was about to be awarded to me, an entire outsider, wholly
unknown to any of the sugar-mill manufacturers of this country.
How often it has occurred to me, and how often have I expressed the
opinion that, in this particular competition -- as in many other
previous cases -- I had an immense advantage over many others dealing
with the problem under consideration, inasmuch as I had no fixed ideas
derived from long-established practice to control and bias my mind, and
did not suffer from the too-general belief that whatever is, is right.
Hence I could, without check or restraint, look the question steadily
in the face, weigh without prejudice, or preconceived notions, all the
pros and cons, and strike out fearlessly in an absolutely new direction
if thought desirable. Indeed, the first bundle of canes I ever saw had
not arrived from Madeira a week before I had settled in my own mind
certain fundamental principles, which I believed must govern all
attempts to get practically the whole juice from the cane; but of
course, there were many circumstances that rendered it necessary to
modify first principles, having reference to the cost of the machine,
its easy transit across country, freedom from repairs in isolated
situations, etc., etc.
In due course I had to attend a meeting at the Society of Arts where I
was much surprised to find the large hall crowded with spectators. At
one side of the room was a raised dais, on which his Royal Highness,
Prince Albert, was seated at a small table, and at his side was the
Chairman of the Committee of Mechanical Experts, who had reported to
the Prince the result of their deliberations. In front of the platform
occupied by the Prince Consort there was a long avenue covered with
crimson cloth, and skirted on each side by rows of seats, occupied by
ladies, who added to their personal charms all that the milliner's art
could accomplish to give grace and éclat to the occasion. It was, I
found, my role to brave all the dangers of this double battery of youth
and beauty; and, like the good St. Anthony, I had to keep my eyes fixed
upon the crimson cloth, for I did not dare to look. If anything could
add to the satisfaction of the moment, it was the presence on this
occasion of the Chairman of the Committee of Experts, who was about to
read his Report, for this gentleman was no other than that talented and
well-known engineer, Mr. John Scott Russell, than whom no one in all
Great Britain was more able to do justice to the subject reported on.
His firm of Robinson and Russell were extensive manufacturers of
Colonial Sugar Machinery, but they had refrained from competing on this
occasion, thus allowing Mr. Scott Russell to add another to the many
proofs of the high code of honour so conspicuous in the whole body of
Civil Engineers in this country, by giving publicly unqualified
testimony to the merits of what was, in fact, the scheme of a rival
manufacturer. The honourable distinction received from such a source,
while it was most gratifying to myself, was more than reflected upon
the speaker.
Among many other things, Mr. Scott Russell, in addressing the Society
and reading his report, said, "the new cane press of Mr. Bessemer has
the merit of introducing a principle at once new and of great beauty
into the process, while reducing the weight and cumbrousness of the
machinery; much has been done by Mr. Bessemer towards removing the main
obstacle to improvements in the working machinery of the Colonies in
the Tropics, viz., the difficulty of transport." Mr. Scott Russell
further pointed out that: "When these facts of facility of transport,
simplicity of foundation, and other advantages come to be considered in
reference to cost, it will at once be perceived that notwithstanding
the great advantages it offers in respect of quality and quantity of
juice, certainty and uniformity of action, and freedom from accident by
wear and tear, the cane press, when placed in working condition upon an
estate, will have cost less than the most ill-constructed mill and
engine to be obtained from the cheapest and most inferior makers."
At the conclusion of Mr. Scott Russell's address there was a round of
applause, and this was followed by the rising of his Royal Highness
Prince Albert, who complimented me in the kindest manner on the success
of my invention -- an invention which I had taken such unusual steps to
prove, by bringing, as it were, the Colonies to us, and by resting my
claims to recognition on actually accomplished facts. His Royal
Highness then placed in my hands a beautiful Gold Medal. In briefly
expressing my thanks, I said that whatever advantages might in the
future result from this invention, they would be entirely due to the
encouragement held out by his Royal Highness; and amid the warmest
recognition from the assembled spectators, I beat a retreat with the
prize I had received.
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