filtered through a soil similar to a nitre-bed, is tainted with substances evidently injurious. So true is it that a condensed population carries in itself the germs of insalubrity,

At Paris, by reason of the geological medium which it passes through, the water collected in the wells is not drinkable; nor is it drunk, or made use of in the preparation of food. According to that, we might suppose the population completely sheltered from the inconveniences which it would produce. This would be an error; for it is easy to prove that every inhabitant takes every day the whole of the substances dissolved in a certain volume of that water.

First, we are convinced that within the city walls the lixivium (coupages) of the heavy wines and alcoholic drinks are mixed with the water of the wells; and it is asserted that the bakers employ no other in making the bread.

One thousand kilogrammes of flour, in making into bread, require for the different leavens and dough 617 litres of water.

For produce they obtain 1,375 kilogrammes of bread, containing necessarily all the soluble substances of the 617 litres of water.

In 1 kilo, of bread there is therefore all that is found in 45 centilitres of well water. Let us next see which nitrates this water introduces.

The well water of the Hotel Scipion, the bakery of the hospitals, contains per litre the equivalent of 0.31 gr. of nitrate of potash; this is one of the waters least charged with salts.

One kilo. of bread prepared with this water should contain 0.14 gr; and 1 kilo. made with the water of the well of Rue Saint Landry contains the equivalent of about 1 gramme of nitrate of potash.

In these weak proportions it is doubtful whether the nitrates are unhealthy; but what renders their presence in the bread unpleasant is, that it is the indication of organic matters, evidently proceeding from suspicious sources: from domestic waters for instance, or the infiltrations that escape from the 60,000 privies sunk below the soil. We must not forget, also, that every year, by the rising of the Seine, the subterranean inundations put in communication the inferior with the upper strata of the soil, in the latter of which are the receptacles of the night-soil, &c., and that the waters in washing the soil convey, in what they draw, spores of cryptogamic vegetation-those mouldinesses always hurtful, and so much more to be dreaded that their organism, apparently so frail, resists nevertheless the temperature of the oven in baking bread, as laid down by M. Payen, and more recently by M. Pagiale.

In a memoir read before the Academy in 1852, I have already spoken of the disgust inspired by the well water when we know, and no one is now ignorant of it, that they are employed in the bakeries. Already, if I am well informed, the administration of the hospitals have

made arrangements for procuring the water of the Seine to the bakehouse of Scipion. This is undoubtedly an example that will be imitated; for we cannot comprehend why, at Paris, they should persist in preparing bread with impure water.

From the whole of these investigations we may justly conclude that with regard to the fertilizing principles they bring to the earth by irrigation or absorption, the waters which circulate on the surface, or at a slight depth, act much more by the saltpetre than by the ammoniacs which are found in them. In my paper on the ammoniacs of the waters I have shown that river water rarely holds above 0.2 gr. and spring water 0.02 of alkali per cubic metre; now the results hitherto obtained indicate in a cubic metre of the same waters the equivalent of 6 to 7 gr. of nitrate of potash, answering, as azoteous manure, to 1.10 gr. of ammoniac. These numbers are very nearly the same as those deduced by M. Bineau from his chemical studies on the waters of the basin of the Rhône.

The geological constitution of a country has likewise the most decided influence on the proportion of saltpetre. This influence, which is stated by M. Bineau, is above all revealed in the course of this work. Thus, in the lakes hollowed in syenite the waters exhibited only traces scarcely appreciable of nitre; those which proceed from the red or quartzose sandstone of the Vosges appear not to have more than 0.5 gr. per cubic metre; whilst in the calcareous lands, as they belong to the trias, to the jurassique country, to the cretaceous group, or to the tertiary deposits above the chalk, the spring and river waters have furnished the equivalent of 15 gr. per cubic metre of nitrate of potash, and the proportion has varied from 6 to 62 grammes.

If in the springs and rivers there is generally more of nitrates than of ammonia, the contrary seems to exist in rain and snow water and dew.

From experiments continued for six months in 1852, we established that meteoric water, collected from a

great distance from inhabited places, contain on an Messrs. Lawes and Gilbert have found a number nearly average 0.74 mgr. of ammonia per litre. Since then similar, by observations during a whole year, at Rot

hamstead.

BOUSSINGAULT,

Member of the Academy of Sciences, and of the Central Society of Agriculture.

offer to the supply of water be sufficient, no one would think of laying them at closer intervals or at greater depths than in soils of a similar nature, but situated in less rainy districts. The nature of the soil itself-the more or less retentive texture of its constituents-the topographical position and plane of the surface, are the objects of much more immediate and indispensable considerations for the regulation of depth and intervals than the quantity of rain that may generally fall during a whole year. A rain gauge, even assuming that the instruments now used are accurate-and Mr. Denton tells us that upon this important point there is a conflict of opinions-can only give us the quantity of rain that directly and perpendicularly falls over a plane area; but it does not register the quantity of water which, in addition to that direct fall, flows over underlying lands from neighbouring hills, or surface undulations, and other causes, in which case, the register of the rain-gauge is of no earthly use. Again: it often happens, even in those districts where the rainfall is the least, that at any moment showers, such as frequently accompany thunder-storms, will rush upon the land, and in a few moments pour upon its surface a large quantity of water, which of course the drains must be capable of discharging.

It is very obvious that in wet climates the drains are brought into more constant use than in drier ones. But we contend that this is the only difference, and that difference can hardly be practically taken into account in the laying of drains; for however small the yearly average fall of rain may be, the drains may be called upon to discharge at any given moment quite as large a quantity of water, although less frequently, as in lands situated in more rainy districts. We cannot, therefore, understand what practical use in drainage the accurate register of rainfall can be; for the only local circumstances we know of, that must regulate the depth and intervals between the drains, is, as we have said: the nature of the soil itself, and the topographical position of the land in respect to the supply of surface water that may flow from adjacent rising grounds, to a much larger amount than that given by the rain-gauge, and of which that instrument cannot give the most fractional idea. Besides, whatever the fall of rain may be, or, in other words, however often the drains may be called upon to act, this cannot interfere with the intervals and the depths at which the drains should be placed; for the extent of those intervals is exclusively determined by the nature of the soil, and should be limited only by the point where the action of the drains ceases to act laterally the limit of the action of one line of drains ending where the action of the next line begins.

The phenomena exhibited by the movement of liquids are ever the same. If a shower falls over the great desert of Sahara, where rain is seldom seen, its descent downwards through the soil, sandy though it be, is regulated by the same opposite forces of gravitation and

capillary attraction as when falling in countries where rain falls more frequently. It is true drains would be more useful in one case than in the other; but surely an accurate register, such as Mr. Denton advocates, is not necessary for ascertaining that plain fact, the experience of the most ignorant old inhabitant of a district being amply sufficient. In all cases where thorough drainage is aimed at, drains must be laid under every variety of circumstances, at such a depth and at such intervals that the limit of the action of one line terminates where that of the other begins, whether that action is to be exercised only one day in the year, or two hundred days.

When we say that there are districts with a rainfall of 50 inches, and others with only 25, we do not mean that every shower falls with twice the intensity upon the one as upon the other: we only mean that rain falls twice as often, or, in other terms, that the drains are called upon to act twice as often in one case as in the other; but to all intents and purposes the quantity of water which they must evacuate in a given time is pretty much the same.

Then, there are other circumstances which have a direct influence upon drainage, which the rain-gauge cannot reach; and these circumstances, as regards that influence go far to compensate the difference of rainfall between the western and the eastern districts of this country-we mean the fall of snow. It is a wellknown fact that snow is a rare occurrence in Cornwall and Devonshire, whereas it accumulates sometimes to a great depth in the eastern counties. When that mass of snow comes to thaw, with all its accumulations against every obstacle, what becomes of the land, in the spring of the year, when a high temperature and dryness of soil are necessary for the purposes of vegetation, if, on account of the register of the rain-gauge, a deviation from the general rules of drainage had been ventured upon? It strikes us that no rain-gauge has yet been constructed so as to give anything like an accurate datum of the quantity of water brought down in a fall of snow, drifted as it generally is by a high wind. As regards the means of effecting the general register of rainfall in this country, at a cost of some £26,000, as advocated by Mr. Denton, we are pretty confident that no Chancellor of the Exchequer will ever be found to debit his budget with such an item as this, even if it were admissible that sufficiently diligent and careful individuals could be found to undertake such a task for the remuneration of five pounds per annum !

Apart from this anxiety of Mr. Bailey Denton to prove too much, and to overstretch the importance of the measure he advocates, his paper is replete with instructive facts, and shows a great accuracy of observation, and wonderful ingenuity in arranging the results of his experience. His tabular records of the Hinxworth drainage are certainly the best arranged we have

ever seen.

of new

now patent beaters, of different sorts, that may be said to perfectly extract corn from the ears without splitting or breaking it. They are adapted to damp, as well as dry stuff; and also save power, by being of a more or less wedge form, and so cleaving their way through the air, instead of driving it like a fan. At the Gloucester Meeting in 1853, and at Lincoln in 1854, about twothirds of the combined-machines thrashed clean, or nearly so; and about the same number did their work without breaking the grain. At Carlisle, in 1855,

all the machines thrashed perfectly clean: two-thirds completely avoided splitting; and two other machines, out of the nine tested, were nearly as meritorious in this point.

As regards the state of the straw, at Gloucester twothirds, and at Lincoln not half the machines, delivered the straw whole; and at Carlisle only two machines were considered perfect in this respect; while four others out of the nine nearly equalled them. But breaking the straw is a fault or an advantage, according to the purpose for which the straw is intended; and in districts where it cannot be sold, and is consumed as fodder or litter for cattle (and unless it is being thrashed for thatching), farmers prefer to have it well broken. Altogether, the performance of the strictly thrashing part of the machines left little to be desired in regard to the quality of the work; and in two years and a-half since that time, various improvements have been introduced. The time and power requisite for thrashing a given quantity of corn varied very much in different machines; and no doubt we shall find a great advance in these particulars, when the dynamometer is applied, between the engines and machines next July.

At

The processes of extracting the grain free from straws, ears, or chaff, delivering the clean straw by itself, and separating the chaff and pulse, colder or cavings, are not yet conducted in the most desirable manner. Gloucester half the machines were thought to shake the straw perfectly clean, and one nearly so; at Lincoln three machines performed clean shaking, and seven more out of fourteen nearly equalled them; but at Carlisle there were only two out of nine machines which carried absolutely no grain over with their shakers, four others being only slightly defective; while there was plenty of room for improvement in the rest. So far good, as respects the two "perfect" shakers; but a quarter of an hour or twenty minutes' time of working is not long enough to detect the liability of the slats, screens, bars, or meshes of the shakers to collect choking straws, and gradually impede the passage of corn through them; for what are at first considered good shakers will sometimes be found to foul themselves in hour after hour of jumping underneath such stuff as straw and broken cavings of all imaginable lengths, bent in all possible forms, tossed in all postures, and traversing across the area of the shakers in every sort of direction. Freedom from liability to choke is a particular, however, in which many advances have lately been made. Another important consideration is, that this continuous clean-shaking shall be effected by simple mechanism, avoiding as far as possible all shock and unsteadiness to the machine framing, and excessive wear of brasses or working parts. Now, as the effectiveness of the process of shaking depends upon the most complete and repeated tossing or striking, as well as thinly distributing, or drawing out the bulk of straw, so that it may give the enclosed corn and chaff every chance of dropping out, some of the most thorough shakers are objectionable in their motion; while, on the other hand, some of the smoothest and easiest running imperfectly perform their work. How smooth and beautiful is the action of the rotary shaker, which dances the straw over a succession of revolving rollers armed with curved rakes or teeth! Yet, simple as are the means by which motion is communicated to these rollers, how many parts and small bearings there are and the effectiveness of the work (at any rate at Carlisle) was far from perfect. But so important is the steadiness which it gives, the absence of shocks, and consequent smallness of wear and repairs, and freedom from gulling brasses and breaking shafts, that the principle is worthy of all attempts to increase the efficiency

of its action on the straw. Box shakers appear to be the most general favourites with machine makers. The original parallel-motion spars thoroughly extracted the grain and chaff by their blows underneath the straw; but something more resembling a riddle or screen was required to prevent straws from dropping through lengthwise; and when boxes with wire meshes or perforated sheet-iron were found to catch and block up with straws, or else let them through, ingenuity devised slats of various forms to let through the corn, chaff, and pulse only. Then we had rocking-bars or slings at the outer end, thus relieving us from one of the crankshafts, with all its wear and annoyances. However, if you diminish the tossing action of the boxes at one end, you must increase it at the other, either by greater speed or a further rise and fall, or else keep the straw longer upon the shakers in order to receive its due amount of blows. This latter plan is effected by prolonging the boxes beyond the vibrating bars; but in so holding back the straw, it is of course crowded closer together than if it had free passage over, and this principally at the point where it most of all needs opening, scattering, and dancing as lightly as possible-that is, just where the last few kernels are to be let fall out of the whole mass of straw. As a compromise between the parallel-motion, with crank-shaft at each end, and the vibrating at one end and rotating at the other, there is the plan of having half the boxes rock at one end and half rock at the other. Four boxes are the most common, but three have been tried, and we have seen two worked with admirable effect, though of course requiring a rapid speed. But the table shakerthat is, a screen all in one piece the whole breadth of the machine-is capable of turning out the best samples of long straw and cavings, as there are no apertures (as between boxes) where straws can get down, and nothing can pass except through the meshes. When constructed like a wire screen, however, straws will entangle and collect in it; and, if made with slats of wood or hoop-iron, the weight would become an obstacle to its jumping movement. The peculiar motion secured by the short slings on which it swings is precisely that well adapted for keeping the straw "lightened up" and loosely tossing, and as severely chucked and bounced at Now, cannot this be retained, and yet the shaker one end or one part of the shaker as it is at another. divided, so as to give a smooth and regular compensating movement, one half rising while the other is falling, and without additional slings (tiresome things) or additional complication? Suppose it made in twe parts, not side by side, but one following the other, and each extending the same breadth as at present. Retain the present slings, one pair supporting the inner end of the first screen or table, and the other pair supporting the outer end of the second. Where the two shakers both are to be hung upon cranks or eccentrics on a meet half-way, the first is to overlap the second, and shaft placed across underneath, as for driving boxshakers. We should say that this arrangement would obviate the chief objections which the table shaker is now open to.

Separating corn from the chaff and cavings as they come from the thrashing machine must necessarily proceed on a different principle to the shaking of the straw in order to extract these products. Pulse, calder, cavings, chaffings, or whatever you call the short bits of straw and empty ears, can be divided from the grain and chaff by screening, sifting, or straining away the latter through a riddle; but as pieces of straw can penetrate endwise through an aperture large enough to pass chaff and corn, the aim must be to keep them horizontal, and avoid any tossing motion that might turn up ears or straw into an inclined or upright posi

tion above the holes or meshes. The holes in a shaker may be small, yet the straws dropped through are many inches in length. In riddling, all these straws must be prevented passing through holes large enough for the corn; and this can be done only by causing them to travel across the screen without jumping and falling upon it as they do in a shaker. Revolving riddles, desirable as their even regular motion may be, cannot answer, unless, by means unseen at present, they are made to avoid the rolling and tumbling of the pulse upon the meshes or slat apertures; and contrivances for drawing or pushing the stuff across fixture riddles are also completely objectionable, from their heaping and gathering of the corn within lumps of the cavings, instead of thinning all out as much as possible, in order to facilitate the escape of grains and chaff. We cannot imagine anything for the purpose better than the hori zontal jogging motion given to our present riddles, the riddle itself being slightly sloped so as to give every particle of stuff upon it a tendency to travel in one direction over its surface. If all the bits of straw, &c., were of one length, and all traversed the riddle in the same posture, lying either lengthwise or crosswise, it would be easy to shape slats or other divisions of the riddle into apertures that would be bridged and slipped over by the straws while admitting the corn and chaff to pass through. But the difficulty is, that the stuff lies in all directions, and is of innumerable sizes. The aim must therefore be to form the apertures of a shape-say round, square, or but slightly varying from these figures-so as to present equal impediments to the entrance of the straws or ears in every direction. A wire screen with square or hexagonal meshes, or sheet metal perforated, might answer the purpose very well for a short time-that is until it became clogged with caught and doubled straws-provided that no straws dipped and poked their ends beneath the wires, and so became gradually jogged underneath (that is, through) the riddle, instead of being conveyed over the top. Hence it is indispensable that sloping walls or partitions should be given to the apertures, at any rate on that side opposite to and meeting with the advance of the stuff, in order to hinder the passage of straws in a downward direction, and by their inclined surface raise up any dipping-ends on to the riddle again. This is a most important point in the riddling apparatus; and we advise purchasers of combined thrashing machines to be very particular in their choice; for when the riddles have any tendency to clog and block up, and continual attention needful in clearing them, not only time is lost in frequent stoppages, but waste of corn is inevitable. Now, for passing off the straws endwise without any poking through, and at the same time for presenting apertures that no mass of chaff and corn ean by any possibility choke up, we have the slat riddle, resembling a Venetian or louvre shutter, with the slats inclined say at 45 degrees. This form was originally intended also for having a blast underneath, which blowing up through the spaces, and meeting the corn and chaff, should separate the latter, as well as tend to lift and throw off the pulse above. But we do not approve of this principle, preferring (as we shall hereafter show) to separate the pulse by simple straining or sifting, and reserve the whole force of the blast for chaffing in a different manner. To prevent straws from dropping through transversely, wires were introduced, passing through holes pierced in the slats. To gain more aperture space, and obtain the raising action of the inclined slats on the opposite side of the spaces, angle-bars, with their edge uppermost, have been adopted; and another application of the principle of a sloping passage, or aperture, is seen in the riddle, made by boring round holes in a slab of hard wood, the holes slanting toward the blast, and widening down.

wards, so as not to choke. But, seeing that corn may possibly ride over this latter riddle upon the thick, though tortuous, interstices or partitions, although no pulse can penetrate through, and that straws may cer. tainly drop between the angle-bars of the other riddle, or lodge across the wires between the slats of that first mentioned, our readers will be willing to receive our special approbation of a slat-riddle constructed as follows: The slats are to be of hard wood, half-inch stuff, before planed up, and say one and three-quarters inches deep; make them into a riddle, by letting their ends into a rectangular deal frame as wide as the machine will allow, and of sufficient length (to be noticed presently); the slats lying square across the frame, and inclined at an angle of about 45 degress; the distance apart, measuring from middle to middle of the (parallel) slats, is to be one and a-half inches at the inner end of the riddle, and gradually less till it is one and a-quarter inches at the outer end. Thus far we have simply a slat-riddle, made slightly to vary in the size of aperture, according to the bulk of stuff upon it at different parts, this being of course much less toward the outer end, when most of the corn and chaff has been parted with, than it is when first entering upon the riddle. But now fix wires (rather fine), lengthwise of the riddle, upon the top of the slats, crossing them at right-angles, fastening each wire to every slat by small wire staples; the wires to be one and a-quarter inches apart. This improved form of riddle, contrived by a mechanically-gifted farmer in Cambridgeshire, and since adopted by some great manufacturers (in one case strips of cane being substituted for the rusting wires and their tiresome staples) works to perfection, or comes very closely to it, whether for wheat, barley, oats, or peas. It is just possible that improvement may yet be made in avoiding still further the wear, or liability to damage, of a riddle rather tedious and expensive to make, and rendering it utterly impossible for short ears to drop through or catch under the wires at the corners. At present there are a few refractory bits that will make their way through, and require to be arrested by the smaller chaffing riddle to which the corn, &c., is next conveyed. And we may say here, that no riddle must ever be expected to be absolutely perfect in its action, and that therefore we ought not to trust to a single riddle, but employ a second (of smaller dimensions and diminished apertures) to rectify the occasional omissions of the first, besides the extra facility we may thus get for chaffing. We have alluded to the length of the riddle. It is a common error to have them much too short, and adapted pretty well perhaps to a steady and regular supply of stuff. But the supply is often very irregular, partly owing to sudden thrusting in of whole sheaves at once by the man feeding, partly to the gathering together of lumps of stuff (especially when damp) either upon the riddle or on the way to it; and we ought to provide for such extreme and extravagant amounts of stuff at any instant, if we would prevent waste and produce a pure sample. The farmer above-named has his riddle 4 feet long, and would like to stretch it another foot at least, to make it equal to every emergency. His chaffing riddle, which stops the escaped odd pieces of pulse, is about 2 feet in length, made with slats at similar intervals to the other, only the wires are inch instead of 11 apart. Instead of crowding the stuff upon a restricted surface, let the principle be to spread and open it out as much as possible, by causing it to pass quickly over the riddle, and hence a considerable length is necessary in order to give it due time for letting fall the chaff and corn. Another point to be borne in mind is, that corn may ride upon or within a knot or braid of doubled or intertwining straws, and so be carried over with the cavings; there