and 8ft. wide. The total quantity of stone in the bridge is 1,400,000 cubic feet.

nence.

1 sq. in. bar of Swedish iron has a tenacity short links of an oval form,
the links being no longer

9.7 tons
11:375 sq. in.

=

than is necessary to permit

FIG. 4

=

the smith to use his tools

for soundly welding the

=

Ere it was opened for traffic it had to un-
dergo severe tests to ensure stability and perma-Tensive strength = (11-375 × 97) sq. iu.
The first and principal experiment con- 110-3375 tons say 110 tons.
sisted in passing two locomotive engines through
the tube, and resting them at intervals in the
centre of the sections. Another trial was a train
of 28 waggons and two locomotives, with 280
tons of coal, drawn into all four tubes.. The
deflections caused by these loads were ascertained
to be exactly three-fourths of an inch over the
immense mass and area of iron.

cular brass tube whose outer diameter
IV. Required the tensive strength of a cir-iron. Chain cables for ships,
= D or for raising sunken ships
are made with the links
somewhat longer, and a stud
(see Fig. a) or stay is in-

With the aid of Table I. and the rule, "the tensive strength of a uniform body is directly proportional to its transverse section," we are almost able to determine the tenacity of all materials with which engineers have to deal.

All problems connected with the tensive strength of bodies are reduced to two, or, speaking more concisely, to one, for one is the mere converse operation to the other. They are:

1. Required the tensive strength, or the constant load, a body will safely bear when the dimensions of the transverse area are given ?

2. Required the dimensions of the tranverse area of a body when the tensive strength of the same material is known per square inch of sectional area?

19.9 x 156 tons 31-044 tons = strength.

3.14 =

3.52

4

4

ส่ง

9

7.06 sq.
Area or space contained between them
2:49 sq. in.

1 sq. in. bar of brass tube has a tenacity

=

=

(2:06 × 2·7) 5562

2.7 tons.
2:06 sq. in.
Total tensive strength
tons, say 5 tons.
By aid of the above examples the student will
find no difficulty in ascertaining the tenacity of
any material having a given sectional area, or
conversely in finding the dimensions of a piece
? of material to bear a certain load, so that we
may now proceed to

=

total cohesive

II. What is the cohesive power of a round bar of cast steel 2.5in. in diameter.

THE TENACITY OF CHAINS AND ROPES.

Metals when drawn into wire become stronger
in respect to tensive strain, (see Table I.), owing to
the wire-drawing process, causing the particles
to arrange themselves in continuous fibres.
Numerous experiments show that iron wire up
?to one inch diameter attains a strength of about
per cent. greater than that of iron bar; so
that while the strength of wrought iron wire may
be taken at 8 tons per sq. in., that of iron wire may
be taken at 11 tons per sq. in. nearly.
Chains are now so well and so accurately
made, and their

6.25 circ. sq. in.
(157 × 6-25) tons = 98.125 tons = total cohe-
sive strength.

We could have found the total cohesive strength without making use of col. 3 in the table, as follows:

The area of a circle whose diameter is equal to (diameter)2

2.52

30

soundness and
qualityso readily
ascertained by
means of the

× 3·141: =4898 sq. in. 1 sq. in. bar of testing machine,

cast steel has a tenacity 19.9 tons 4.808 sq. in.

- ?

crane

that they are
much used in
work on
ships, &c., in-
stead of ropes,
for
especially
but as there are
outdoor work;
many circum-
stances in which

it may be requisite to use ropes, it will be proper
to show the strength of both.

The strength of a chain is determined by as-
certaining the diameters-all are equal to each
other of the metal constituting the links;
thus the chain which has a diameter of an inch
at A is called an inch chain, and so on.

serted in the link across its least diameter, to support the sides and prevent their collapse under heavy strains, thus giving great additional strength to the chains. The latter are nowadays more or less done away with, and are replaced by a method patented by Austin in the year 1837, which consists in fastening empty gutta percha vessels or balloons to the ship's sides, and filling these by means of an air-pump with air.

Since studded chains used for cables are stronger than short linked chains without studs, it is not prudent to subject both kinds to the same proof, when the tenacity of the chains is tested.

The proportions existing between short linked chains to a studded chain is as 7 is to 9, or a simple chain able to sustain a "proof weight" equal to 14 tons-being the proof strain of one inch chains-will when studded be able to carry 18 tons, which is the Navy proof for iron cables. Both kinds may be safely worked to half the strain to which they have been proved.

The tenacity of chains is generally tried at a mean temperature, the strain being steady, and the vibration caused by the blows of the hammer, given in order to detect imperfect welding of a link, is by no means equivalent to the live loadi.e., one that is put on suddenly-it will have to sustain, when exposed, perhaps to a temperature below the freezing point, affecting the strength of iron, as it does that of all crystalline bodies.

The following are the two practical rules for calculating the diameter, or working load of an iron chain, for computing the tenacity of chains, being calculated at a lower rate than they are generally stated, as it is best to be on the safe side, when we consider what great damages often result from the breaking of a chain, and what is still more carefully to be guarded against, serious injury to life and limb, is inflicted.

1. Extract the square root of 8 times the safe load, and the result will give the diameter in eighths of an inch, or in symbols, if d = diam. in eighths of an inch, W=safe load in tons, then d = 8 W; or

2. Multiply the weight (tons) to be carried by 30; the product will be the square of the dim. of the chains reckoned in sixteenths of an inch. Where long chains required to lift heavy loads are used, it is best to work out the diam. after the first rule, as it gives a little larger diameter to the chaih.

Example: Required the diam. of a simple chain to bear a safe load of 14 tons. a (by rule I.)

Within certain limits the strengths of chains
may be estimated in proportion to the squares of
the iron's diameter of which they are made; but
it is obvious that when they are made very large
or very small, neither the quality nor the work-
manship can be so well relied upon. Iron of
large diameter is less fibrous and more crystal-
line in the fracture, and the welding is more
2.2 6.875 sq. in.
perfect in links of intermediate size. Mr. Glynn
for this reason recommends that chains above an
product of two adjoining inch in diameter should not be employed for
crane work, as he prefers chains of smaller di-
mensions, say, , or of an inch, and reducing
the strain upon the chain by increasing the (by rule II.)
number of the parts that bear it, by means of
122 144
blocks and pulleys.

Area of rectangle
side 15 x 3 = 4.5 sq. in.

Total area = 11:375 sq. in.

According to Euclid, the areas of circles are directly proportional to the square of their diameters, and the product will be the ultimate cohesive strength.

Chains for crane work, are commonly made with

Example: What safe load will a chain (simple) bear having a diameter Ain. a (by rule I.)

6'

--

8

36

8

=

=

41⁄2 tons: say 4 tons.

4

Broke with strn. of 4500lb. (white) & 3400 when tarred the mine, and having fixed studs, D, attached.

Mons. Du Hamel says that it is a decided fact 52. A and B are two rollers which require to by experience that white cordage in continued be equally moved to and fro in the slot, C. This service is one-third more durable than tarred; is accomplished by moving the piece, D, with secondly it retains its force much longer while oblique slotted arms, up and down.

kept in store; thirdly it resists the ordinary in-accidents in case of the breakage of machinery 53. Centrifugal check-hooks, for preventing Juries of the weather longer.

SKINS.

southern hemisphere. The toes are fully webbed, SHEARING OR CLIPPING ANIMALS AND
the hind one wanting; the plumage is black,
excepting the under parts, the tips of the wings,
and an oval spot in front of each eye, which are

THIS invention, patented by E. H. Rawlings,
relates

pensed with, and replaced by a parallel motion
the con necting rod I being attached to the arm B
of the knife by the link K, and guided in a slot
L in the plate A, in which slot it is retained by
means of a pin, having a he or 911 a
back or ander side of the plate A.

CHAPTERS ON CURIOUS CATER

M

PILLARS.
MAY.

the

the autumn

BY J. R. S. CLIFFORD. -AKING due allowance for the difference Faroe Islands, Iceland, Greenland, and Newfound- the class in which the hair or wool is cut by a between early and late seasons, we shall land. "Degraded as it were from the feathered reciprocating knife working upon the surface of rank (said Nuttall), and almost numbered with a comb, and consists, 1st. In the peculiar forma- find that caterpillars generally are more abunthe amphibious monsters of the deep, the auk tion of the comb; 2nd. In the employment in dant during May than at any time during the seems condemned to dwell alone in those desolate combination with the comb and knife of a spring and summer season. These, having at and forsaken regions of the earth." But it was novel device for keeping the knife properly and tained maturity, pass into the chrysalis state, and an unrivalled diver, and swam with great velocity. evenly in contact with the comb; and 3rd. In undergo one of two destinies-they either appear, One chased by Mr. Bullock among the Northern the mechanism for imparting motion to the said Isles left a six-oared boat far behind. It was knife. Fig. 1 is a top view; Fig. 2 is a similar as perfect insects some time dur undoubtedly a match for the Oxfords. It was view of a modification of the same. A is the or put in an appearance in the early spring; or, finally shot, Lowever, and is now in the British comb or toothed plate, and B is the knife which almost, perhaps, before we can say it is spring, Museum. "It is observed by seamen," wrote has two cutting edges; C and D are the handles though an occasional twitter of a bird, or the Buffon a hundred years ago, "that it is never whereby the apparatus is held and operated; E swelling buds on shrub or tree hint to us that the seen out of soundings, so that its appearance is a bridle or bridge which is placed over the serves as an infallible direction to the land." It knife, and is so formed and arranged that the vernal time is approaching. Of this latter class fed on fishes and marine plants, and laid either knife works in contact with its under surface, is the moth of which the transformations are in the clefts of the rocks or in deep burrows a and is thereby kept evenly in contact with the now described, its time of appearance being solitary egg, five inches long, with curious mark- comb throughout the extent of its course; F is a February, or the beginning of March. During ings, resembling Chinese characters. The only toothed segment pinion to which the knife is the month of May, in those places where noise it was known to utter was a gurgling sound. fitted and secured by the screw F, the latter is the species occurs, the caterpillars are sufficiently Once very abundant on both shores of the North secured in the plate A, and may be readily reAtlantic, it is now believed to be entirely extinct, moved when it is desired to change the knife. conspicuous from their mode of life to attract the none having been seen or heard of alive since The pinion F is geared into the segment G, which notice of observers who are not entomologically 1844, when two were taken near Iceland. is attached to the plate A by the screw H, inclined. The small Egger Moth (Eriogaster whereon it is fitted to work freely. To the seg-lanestris), to which we have been alluding, dement G is connected one end of the rod I, whose posits its eggs on the twigs of the hawthorn, and other end is attached to the elbow lever D1, on it would appear as if usually the whole number which is fixed the handle D. The bridle or bridge of eggs which each female is possessed of are E is secured at each end to the plate A by screws E1, between whose heads and the bridle are spring washers, and the pressure of the said bridle upon the knife may be regulated by adjusting these screws. The stroke of the knife is limited in each direction by the stops J fixed in the plate A. By means of the comb or toothed plate A the hair or wool of the animal to be sheared is raised, and the toothed part of the said plate is so formed and arranged that the knife at the commencement and end of its course in each direction lies entirely beyond such toothed portion, as shown, so that the hair or wool may be taken up without obstruction between all the teeth from one end to the other thereof, and so that no hair will remain caught between the teeth and the knife when in the operation of shearing the apparatus is raised or moved backward or forward. The handle C serves as a the means for holding and guiding the apparatus with the left hand, while motion is imparted to the knife through the connecting rod I by the lever D1 and handle D. Pressure of the knife upon the comb is produced by means of a spring washer placed at the axis or centre thereof, which

The death of a species is a more remarkable event than the end of an imperial dynasty. In the words of Darwin, " no fact in the long history of the world is so startling as the wide and repeated extermination of its inhabitants." What an epoch will that moment be when the last man shall give up the ghost! The upheaval or subsidence of strata, the encroachments of other animals, and climatal revolutions-by which of these great causes of extinction now slowly bat incessantly at work in the organic world, the Great Auk departed this life, we cannot say. We know of no changes on our northern coast sufficient to affect the conditions necessary to the existence of this oceanic bird. It has not been hunted down like the Dodo and Dinornis. The numerous bones on the shores of Greenland, Newfoundland, Iceland and Norway, attests its former abundance; but within the last century it has gradually become more and more scarce, and finally extinct. There is no better physical reason why some species perish than why man does not live forever. We can only say with Buffon, "It died out because time fought against it."

From the Lingula prima to the Auk, genera have been constantly losing species, and species varieties; types and links are disappearing.

placed in ones pot. These eggs are covered with down, which the parent strips off the abdomen, its hue being blackish, or smoke-coloured. This, serves to protect the eggs from the rain and cold of the season, and when April arrives, the young caterpillars begin to hatch out, having sometimes a difficulty in disengaging themselves from their downy envelopment. In habit they are gregarious nearly throughout their life, constructing a nest or web, in which they repose, and devour the leaves around it, extending their excursions by degrees to some distance from this home. As they increase in size, with successive changes of skin, they remove from place to place, constructing new abodes, until the tiny nest, which at first might have been hidden in the palm of the hand, gives place to a structure of some size, which the insect hunter pounces upon with satisfaction should he come across it. In this common nest they generally contrive to include one or two largish branches, on which they cluster when not eating, lying extended at full length. If one of these caterpillars is alarmed, he suddenly raises the head and the front segments, assuming some

what of the attitude of the Hawk Moth Caterpillars, and if still further disturbed, then falls compacted into a ring. After the last change of skin, the caterpillars of the Small Egger separate and feed alone, but it would seem as if this were not invariably the case. The general colour is velvety black; along each side there runs a narrowish yellow stripe, from which, on each segment, a slender brauch goes off at a right angle; the body is clothed with hairs of two different lengths, the shorter hairs being rich brown, the longer paler, with greyish tips. The legs and the hindmost pair of claspers are black, the rest of the claspers being red. The cocoon formed by this caterpillar has given its name to the moth; it is egg-shaped and compact, and so small, as compared with the size of the caterpillar, that it is difficult, when the two are placed together, to imagine how it can be constructed, as the caterpillar must, of course, work at it from the inside. Not only, however, does it complete this cocoon in the most perfect manner, but it leaves, with great dexterity, two or three small holes in this encasement, the purpose of which is doubtful.

66

GEOGRAPHICAL INFORMATION.

INTRODUCTORY.

When

"devil's-bit scabious." The winter is passed by scends to the ground, feigning death. them in a state of hybernation, under the protec- resting, the body is extended in a stick-like position of a silken covering; in the spring, how- tion. ever, they feed exposed, and seem even to de- One of our most active moths is that approlight in the rays of the sun. The caterpillars priately called the July Highflyer (Ypsipites of the Greasy Fritillary are black, or deep brown, elutata), and the habits of the caterpillar prowith reddish-brown claspers, the surface of the ducing it contrast singularly with those of the body is sprinkled with white dots, and is also mature insect. This lives through the winter, covered with spines rather thickly set. In the and feeds up in the spring, being full-grown in good old times," this insect occurred at Chelsea, May. It lives upon the sallow, generally hiding in the immediate vicinity of London; it must during the day in the masses of seed-down, and now be sought in localities remote from the me- coming forth at night. It is slow in its movetropolis. The butterfly flies very tardily, and ments, and falls at once, as if inanimate, when may be easily caught with the hand. it is touched. The colour is pale brown or Mr. Newman has described with great acu-smoky brown, the body being marked with white men the history of the Heath Fritillary (M. stripes, some of which are indistinct, and it is Athalia)-so called because it is most par- slightly attenuated towards the head, which is tial to heathy spots in or bordering upon clear brown, with blackish cheeks, and slightly woods. The eggs are laid by the parent butter- notched above. The chrysalis is placed in a cell flies in June and July on the narrow and broad- constructed in the seed pods of the sallow, from leaved plantain, and the young caterpillars which the moth appears in July and August, and after feeding a short time, hybernate early close flies at times briskly in the sunshine. to the roots. As soon as their food plants are in leaf they feed again, and continue to feed until Another interesting Egger caterpillar may the plantain is in flower, which flower, Mr. be discovered at this season by those on the Newman notes, they much resemble in colour, sea coast, especially in the south of England. and thus escape some of the assaults of birds, Some time in August, the female moths of the so frequently destructive to caterpillar life. Grass Egger (Bombyx trifolii) drop their pale These caterpillars, like those of all the Fritilbrown eggs at random amongst the herbage. laries, are studded with spines, some of which These produce caterpillars in the course of a are orange and white, and others pure white with week or two, not easily to be found during the black tips; the ground colour being black, on autumn, since they keep close to the ground. which some snow-white dots show conspicuously, Feeding again in the spring, they are of some the under surface is of smoky hue. The chrysize in May, being full-grown at the beginning of salis is short and stout, and attached by hooks to June. When found on grasses they are generally a little web of silk previously spun by the caterobserved to eat from the tip downwards. Though pillar. The Glanville Fritillary (M. Cinzia) reknown as the Grass Egger, an observer who has sembles the preceding in its habits, and occurs in bred many, states that they thrive on the birds' tolerably plenty on the Undercliff, in the Isle of foot trefoil, and will also eat oak, willow, bramble, Wight, appearing to have a preference for rough and furze. Mr. Newman, on the contrary, found ground. Mr. Dawson remarks that, by natural that all the individuals he had in his cages re-instinct, the caterpillars of this species, when fused to eat anything but grasses. Like the pre- young, feed low down on the banks, where the ceding species, the ground colour is an intense growth is most luxuriant, and they are sheltered black; though in this caterpillar there is a from rough weather; and as they increase in triple series of very small white spots along the size they advance higher up the slope, attacking back, which are best seen when the caterpillar is the older plants, to the stems of which they atrolled into a ring, as is its habit when annoyed. tach themselves, and become chrysalides. On the third and fourth segments is an orange mark in the form of a crescent. The body is covered densely with soft hairs. The cocoon is usually placed amongst the sand (for the species occurs on the very margin of the sea), being attached slightly to the roots of the grass; it is brown and compact.

One of the largest British moths belonging to the family of the Bombyces is that known as the Lappet (Lasiocampo quercifolia), and this name is taken from the curious appendages or "lappets" which adorn the body of the caterpillar. This creature lives through the winter, being then only about an inch in length, but in May it has usually attained its full proportions. It occurs on blackthorn, willow, and sometimes on oak, being rather easy to detect from its size, though not by any means common, as far as our experience goes. The Rev. J. L. Wood, however, asserts that he has no difficulty in getting either caterpillar or moth whenever he requires it; but he leaves the modus operandi for the ingenuity of his readers to discover. Different specimens of this caterpillar vary much from each other in colour, being various shades of grey and brown; on the twelfth segment there is a distinct hump, and along the sides the protuberances which give it its rather fanciful name; between the second and fourth segments are two broad stripes of a bluish purple. The cocoon is placed by the caterpillar low down amongst the herbage; it is not egg-shaped, being long and blackish, and within it is swung the chrysalis, which is also black and smooth. The moth is sluggish, and when at rest very much resembles a dry and faded leaf. When fresh from the chrysalis, it has a beautiful bloom upon the wings, which fades in a few hours.

Amongst the butterfly caterpillars, which, found at all, are most likely to turn up in goodly numbers from their peculiar habits, are those of the three smaller Fritillaries belonging to the genus Melitea. These are mostly full-grown about the beginning of May. The commonest is the Greasy Fritillary (M. Artemis), which occurs in damp, low-lying meadows. A year or two ago, as an entomological friend reports, these caterpillars occurred by the thousand in a certain part of Ireland, and were looked upon as a phenomenon by the country folks. They feed by preference on the plantain, sometimes also on the

Amongst the crowd of caterpillars which may be beaten from the hawthorn hedges this mouth, we are almost sure to find the small, but singularly-formed caterpillar of the Chinese character (Cilic spinula), the perfect insect being adorned with silvery scales, supposed to resemble Chinese letters-bence the name. The head of this little caterpillar has a crown, which is cleft in the middle; the body is of a dull brown colour, wrinkled, and having a stripe down the back, and some wavy markings. There are also numerous warts, some largish, some minute; a hump on the eleventh segment, and at the extremity of the body a terminal spike, the hindmost claspers being wanting. This spike is raised in the air, and carried much in the position in which the Puss Moth caterpillar raises its horns. When full-grown, the caterpillar of the Chinese character constructs a small gummy cocoon, which is ingeniously hidden in the angle of a branch or twig. There are two annual broods, and the second usually appears in August or September, remaining as a chrysalis through the winter.

Notable among the insects haunting the vicinity of the metropolis of England, and especially abundant in its northern suburbs, is the moth rather absurdly called the Willow Beauty (Boarmia rhomboidaria), which may be seen sitting quietly in the daytime with expanded wings on walls or old palings. The caterpillars which produce this species are usually adult in May, feeding on the ivy, and giving preference to the large-leaved kind, known as Irish ivy. The eggs are deposited in the summer in little clusters, and the young caterpillars, when newly hatched, eat only partially through the leaves, and, keeping on the underside, are thus protected from the weather. In about a fortnight they begin to nibble holes in the leaves, but long before winter approaches they conceal themselves amongst the recesses of the ivy, spinning a slight web, to which they fix themselves firmly. These cater pillars feed again in April, and when of full size enter the earth, and change to chrysalides just beneath the surface. The colour of the body is brown, darker or lighter, in different specimens ; there are four black dots on each segment, the head is rather darker than the body, notched on the crown with two pale marks, which look like eyebrows. When touched, one of these caterpillars falls at first by a silken thread, and then de

THES
HESE notes, articles, or whatever name my
readers like to give them—do not profess to
be original. They will be simply compilations
condensations from more elaborate treatises. Of
course I have an aim; and it is this to give our
superabundant population, our intending emi-
grants, some bona fide knowledge of the different
lands at the present moment open to settlement.
The ENGLISH MECHANIC having an immense
circulation, and being read by that class to which
geographical information seems all-important, I
have determined, with the Editor's sanction, to
extend far and wide such facts relating to this
subject as are at present known to a select few.
The peculiar information required by intending
emigrants cannot be gathered from any existing
text-books, but is contained either in the minds of
returned settlers and travellers, or scattered
throughout a number of costly volumes beyond
the reach of any but the rich. The so-called
guide books are often terribly inaccurate, as will
be best seen from the sensible remarks made in
he following extract :-

"I greatly doubt," said P, as we strolled away, "the advisability of glossing over all drawbacks (many, very many of which exist) to the intending emigrant. Better far to place the colouring in a fair light, to speak freely of the difficulties he must encounter in soil and climate, and suggest a remedy. A poetical description of scenery in a guide-book may serve to cover over poverty of soil; but the truth is, that the emigrant can't see the poetry of the thing when his crops fail, and then he becomes disgusted with the land of his choice."

The colony is generally represented in an ideal light, as one would wish it to be, but not as it really is. Guide-books, as a rule, omit the failures, giving only one side of the question. This is not the place nor the time to write a dissertation upon emigration; it is a fact that our fellow citizens are emigrating; many have already gone, more are preparing to go. Hard it is to leave old associations, to leave home, kindred, all that is dear, in order to fight the battle of life in a far-off country; but necessity knows no law. Starvation stares us in the face here; affluence, or at least plenty and prosperity are promised there. Nevertheless, an emigrant who would fail to gain a livlihood in one place may become rich in another. Different men are adapted to different countries, and although the Caucasian seems to flourish everywhere, yet it is not so. In India, part of Africa, the "workers" are not the sons of previous workers, but fresh arrivals from the Old Country. An Englishman's childrens' children would soon imbibe and be enervated by the peculiar climatic influences of these regions, but other parts have a climate very similar to our own, and here it is that the race is perpetuated. America, Australia, New Zealand, the Cape, &c., all testify to this fact. Following the example, therefore, of "F.R.A.S.," I shall be glad to answer, when possible, any questions, directed to the Editor in the usual manner. This, I think, will be the best course to pursue, as although many readers would enjoy a descriptive narrative of the journey of Mr. Freshfield amidst Caucasian mountains, or Mr. Williamson in Marchuria, &c., yet the specific object at which I aim would not be gained."

F.R.G.S.

EXHAUSTED TEA LEAVES.
NDER any circumstances, it is a misnomer to

UNDERnnyed tea leaves "exhausted," as

they still contain a large proportion of such material as we every day consume in the form of bread, beef, and vegetables-viz., in Souchong, 4.6 per cent., and in Gunpowder, 4.40 per cent. of nitrogen. It needs but a glance to see that, apart from any putrefactive decomposition which may be discovered in re-dried tea leaves, they are not unfit for human food, if consumed as a vegetable. The use of leaves which had "passed through the pot," as a means of increasing the bulk of tea retailed by certain grocers of "easy virtue," was conspicuously brought before the public by Mr. Phillips, of the Inland Revenue Office, twenty-six years ago. He then remarked "In the year 1843 there were many cases of re-dried tea leaves, which were prosecuted with viguor by the board, and the result was, so far as we could ascertain at the time, the suppression of the trade. It was supposed, in 1843, that there were eight manufactories for the purpose of re-drying exhausted tea leaves in London alone, besides several others in various parts of the country. The practice pursued was as follows:-Persons were employed to buy up the exhausted leaves at hotels, coffee-houses, and other places, at 24d. and 3d. per lb. These were taken to the factories, mixed with a solution of gum, and re-dried. After this, the dried leaves, if for black tea, were mixed with rose-pink and black lead, to 'face' them, as it is termed."

In those days, it will be remembered, owing to the enormously-increasing comsumption arising

DRESSING MILLSTONES WITH THE
DIAMOND OR "BORT."

and level of the millstones as of more impor tance even than the quality or perfection of the UR readers have observed that for some cracking or dress, and recent experience with OU weeks past an interesting controversy has confirm this opinion. We feel sure that every improved arrangements has very much tended to been sustained in our columns on dressing mill-miller who has given the matter consideration stones. Who would have thought that the will agree with us that these two defects are all ENGLISH MECHANIC would have become an but inseparable from the system of dressing by organ for millers? Judging from what several hand-namely, an imperfect dress and a want of correspondents have said, such is the case. truth and level in the millstone face. the question is an important one, not only to millers, but to all interested in the cheapness and purity of flour, we will transcribe from the Engineer a paper on the subject.

As

A remarkable revolution has been in progress during the last two years in a department of the mechanical operations connected with the manufacture of flour, and various facts associated therewith are worthy of record, not only on account of the importance of the manufacture, as supplying the "staff of life" for our daily wants, but also because they possess considerable interest from a mechanical point of view. We do not propose to enter very minutely into detail, nor to deal very largely with technicalities which could interest the miller only at the same time we may have to mention some facts that are most probably known to all our readers.

The character of the grinding surfaces of the

pairs of millstones in the United Kingdom, 80 It is roughly estimated that there are 80,000 that the importance cannot be over-estimated of any sound improvement so essentially affecting their use and action as one relating to the "dressing" of their grinding surfaces. The subjeet has not failed to attract the attention of inventors and patentees, and a great variety of appliances have been proposed from time to time. Amongst these there have been various combinations of mechanism which, in imitation of the ordinary hand-dressing, have been designed to actuate a steel bill or pick, the objects of such mechanism being to render the action more uniform and regular, and to dispense with extreme skill on the part of the operator. Some of these combinations have comprised arrangements for making the lines of the cracking accurately parallel and at uniform distances apart; but in none of those designed for using the steel tool is there any provision for, or arrangement conducive to, the maintenance of the truth and level of the stone; and as none of them have come into use, it may be safely ments of the case.

from various causes, the inducement to adulte- millstones has a great deal to do with the assumed that they have not satisfied the require

rate was much greater than it is now, and the duty levied was 2s. 24d. per lb. Coming to a more recent period, we find that on the 18th December, 1850, the excise authorities seized a quantity of material in Liverpool, expressly prepared for tea adulteration, which possessed the negative merit of containing no tea at all. It consisted of broken sycamore and horse-chestnut leaves, stuck together and rendered astringent with catechu. During the following year another pleasant little episode in the way of sophistication came to light in the classical region of Clerkenwell. The Times of May, 1851, gives a description, which we abreviate:-"Edward South, and Lonisa his wife, were charged with being concerned in the manufacture of spurious tea. The officers had been to their house, where they found the prisoners engaged in the operations. There was an extensive furnace, before which was suspended an iron pan, containing sloe leaves and exhausted tea leaves, which they were in the practice of purchasing from coffee-shop keepers. On searching the place, they found an immense quantity of used tea, bay illicit tea, and these were mixed with a solution of leaves, etc., for the purpose of manufacturing gum and a quantity of copperas. The heat was so excessive that the officers could scarcely remain, but the prisoners did not seem at all oppressed. The woman was employed stirring the bay leaves and

That such vile practices are by no means obsolete, we observed from one of the occasional notes in the first number of this journal; but it is to be hoped that public indignation, once more aroused, will have the effect, through judicious legislation and the continual employment of analytical chemistry, of curbing, if not altogether eradicating, tea adulteration.

quality of the flour produced. After the grind-
ing operation, the flour is separated by "dressing"
or sifting, into different qualities, and from the
same grain one pair of stones will produce a
much larger proportion of the first and finest
quality than another pair. This depends on the
"dress" or surface condition of the stones. The
face of each stone has a number of grooves or
"roads" formed upon it, the surfaces or "lands"
between these grooves being the parts which
effect the grinding operation. It has hitherto
been the practice to produce on the lands the
roughness necessary for grinding entirely by
hand, by means of a steel chisel, pick, or bill;
and considerable skill is required by the operator
or "stoneman," who strikes in a peculiar
manner and so as to just crack the surface of the
stone. The roads of the stone are arranged in
sectors, all in one sector being parallel to each
other, and the "master" or longest road in each
sector being in a radial position. This arrange-
ment is, however, sometimes departed from.
The cracking or dressing is generally done in
minute distances apart.
lines which are parallel to the roads, and at

No attempted improvement in dressing millstones has as yet attained any practical success that has not comprised the use of "bort" for the cutting tool; at the same time, it may be interesting to refer to one of the machines proposed for operating with a steel bill, as not only was it anterior to any proposal to use the diamond or bort, but it also contained various mechanical appliances, which, with suitable modications, have been adopted in the successful bort machines, and its designer may, therefore, justly claim to have contributed something towards the ultimate success. The machine to which we refer is the invention of a Parisian miller, P. J. Morisseau, patented in this country in the name of G. Davies, of Serle-street, on the 9th April, 1861, No. 865, and is shown in vertical section in Fig. 1, and in plan in Fig. 2. The following description is from the specification :

"The machine rests by its own weight upon that part of the millstone A, which it is desired to operate upon, and it may be moved with ease on to any portion or division of the circumference of the stone, being guided in this movemeut or alteration of position by means of two gudgeons or pins fixed at two extreme points of the frame B, and sliding in a circular groove a, made in the iron ring C, which embraces the circumference thereto by set screws.

Millstones when grinding night and day are usually re-dressed by the handbill once in six days. In large mills the stonemen are kept exclusively at the work of dressing, and in conseother materials with a solution of gam in the pan; quence attain as great efficiency as is possible at of the millstone, and is adjusted and fixed and in one part of the room there was a large this description of work. In small mills, quantity of spurious stuff, the exact imitation of "Each of the longitudinal sides of the genuine tea. In a back room, were found nearly tricts, this is not possible, as the men cannot however, such as are scattered over country dismachine is provided with a long screw rod ¿, 100lb. weight of re-dried tea leaves, bay leaves, and sloe leaves, spread on the floor, drying. The wholly occupy themselves with dressing, but have upon which is mounted a bevel wheel c. These wheels have bosses screwed internally, and work prisoners had pursued their nefarious traffic to attend to all sorts of work, and cannot between two projecting pieces forming part of extensively, and where in the habit of dealing attain the same proficiency. With the best and the frame or carriage D. This carriage also largely with grocers, chandlers, and others, esmost careful hand-dressing possible, the millpecially in the country." stoues, for from thirty to forty hours after being extending the whole width of the machine, and supports a long ratchet or grooved cylinder E, dressed, cut up the wheat very much, making to the extremite of which are keyed bevel the meal rough and unequal,-the flour being in consequence specky and irregular, the bran pinions e gearing respectively with the wheels e on the screws b. It results from this arrangement small and badly cleaned, and the proportion of that by the rotation of the cylinder E the flour-sharps, middlings, or second quality, carriage D can be caused to travel the whole large; and in proportion as the millstones are length of the screws, and consequently of the less perfectly dressed these evils increase. In machine itself. On the carriage D are two addition to the importance of the dress or brackets or supports carrying a shaft f, which is cracking being well done, it is also of great grooved throughout its entire length so as to reimportance to have the millstone face, or ceive a key connecting a cam g thereto, which grinding surface, absolutely true and level; cam is intended to communicate motion to the much difficulty, however is experienced cylinder E, as hereafter described. This cam is in keeping the millstones true-the tendency held between two projections or bosses gi fixed being for a portion or section of the grinding on a second carriage F, which carries the cutting surface to get out of truth with the rest. Indeed, tool or hammer m, and also serves as its guide. under the system of hand-dressing it has been This carriage, which is mounted on V slides on found impossible to prevent this evil from the carriage D, is moved by hand by the workarising, more or less, notwithstanding the most man by the aid of a lever h, and can be slidden careful use of the proving-staff. The application from end to end of the machine, and arrested at of the staff to the surface of the stone is the any point desired. The tool cartier k moves only means hitherto in use for testing or indica- vertically in V slides formed in front of the ting the truth or level of millstones, and it has carriage F for that purpose; to this piece are long been felt to be imperfect, a more thorough attached jaws which hold the cutting tool or and accurate method being much wanted. Many hammer, the position of which latter can be practical and careful millers consider the truth regulated to any height desired above the sur

Already the community feels the sting, and it is a significant fact that the 7,000,000lb. of trashy tea, alluded to in Dr. Letheby's report as being under the ban of the City authorities, almost exactly correspond with the quantity of good tea short last year in the imports from China, as compared with those of 1868.

It must be evident from the foregoing, that the time has passed away when we need hold up our hands and roll our eyes in holy horror at the iniquity of the Chinese. Surely it were better to mingle our frugal Congou with Maloo mixture, over which the nimble Shanghai pigs had gyrated, and China dogs gambolled, rather then return to the days of slow poisoning by arsenite of copper, chromate of lead, bay leaves, sloe leaves, and catechu.-Food Journal.