Chapter 10

Indians are not usually as good pickers as white people, but in the sparsely settled districts, where many of the berry farms are situated, it is impossible to get white help enough to take care of the crop in the short time available for the work, and owners are compelled to employ the aborigines. A rake, with the prongs shaped like the letter V, is used for picking in some cases, but owing to the large amount of grass and weeds that grow among the vines on these wild marshes, this instrument is rarely available. After being picked the berries are stored in warehouses for a period varying from one to three weeks. They are washed and dried by being passed through a fanning mill made for the purpose, and are then allowed to cure and ripen thoroughly before they are shipped to market.

From statistics gathered by the American Cranberry Growers' Association it is learned that in 1883 Wisconsin produced 135,507 bushels, in 1884 24,738 bushels, in 1885 264,432 bushels, and in 1886 70,686 bushels of this fruit. By these figures it will be seen that the yield is very irregular. This is owing, principally, to the fact that many of the marshes are not yet provided with the means of flooding, and of course suffer from worms, droughts, late spring or early autumn frosts, and extensive fires started by sparks from the engines on railroads running through the marshes. These and various other evils are averted on the more improved farms. So that, while handsome fortunes have in many cases been made in cranberry growing, many thousands of dollars have, on the other hand, been sunk in the same industry. Only the wealthier owners, who have expended vast sums of money in improving and equipping their property, can calculate with any degree of certainty on a paying crop of fruit every year.

Chicago is the great distributing point for the berries produced in Wisconsin, shipments being made thence to nearly every State and Territory in the Union, to Canada, to Mexico, and to several European countries. Berries sent to the Southern markets are put up in watertight packages, and the casks are then filled with water, this being the only means by which they can be kept in hot weather. Even in this condition they can only be kept a few days after reaching hot climates.--_American Magazine._

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SOUDAN COFFEE.

(_Parkia biglobosa._)

There are valuable plants on every continent. Civilized Europe no longer counts them. Mysterious Africa is no less largely and spontaneously favored with them than young America and the ancient territory of Asia.

The latter has given us the majority of the best fruits of our gardens. We have already shown how useful the butter tree (_Butyrospermum Parkii_) is in tropical Africa, and we also know how the _gourou_ (_Sterculia acuminata_) is cultivated in the same regions. But that is not all, for the great family of Leguminosæ, whose numerous representatives encumber this continent, likewise furnishes the negro natives a food that is nearly as indispensable to them as the _gourou_ or the products of the baobab--another valuable tree and certainly the most widely distributed one in torrid Africa. This leguminous tree, which is as yet but little known in the civilized world, has been named scientifically _Parkia biglobosa_ by Bentham. The negroes give it various names, according to the tribe; among the Ouloffs, it is the _houlle_; among the Mandigues, _naytay_; in Cazamance (Nalon language), it is _nayray_; in Bornou, _rounuo_; in Haoussa, _doroa_; in Hant-fleure (Senegal), _nayraytou_. On the old mysterious continent it plays the same role that the algarobas do in young America. However, it is quite a common rule to find in the order Leguminosæ, and especially in the section Mimosæ, plants whose pods are edible. Examples of this fact are numerous. As regards the Mediterranean region, it suffices to cite the classic carob tree (_Ceratonia siliqua_), which also is of African nationality, but which is wanting in the warm region of this continent.

Throughout the tropical region of Africa, the aborigines love to consume the saccharine pulp and the seed contained in the pod of the _houlle_. Prepared in different ways, according to tribe and latitude, these two products constitute a valuable aliment. The pulp is consumed either just as it is or as a fermented beverage. As for the seeds, they serve, raw or roasted, for the production of a tea-like infusion (whence the name "Soudan coffee"), or, after fermentation in water, for making a national condiment, which in certain places is called _kinda_, and which is mixed with boiled rice or prepared meats. This preparation has in most cases a pasty form or the consistency of cohesive flour; but in order to render its carriage easier in certain of the African centers where the trade in it is brisk, it is compressed into tablets similar to those of our chocolate. As these two products are very little known in Europe, it has seemed to us that it would be of interest to give a description and chemical analysis of them. We shall say but little of the plant, which has sufficiently occupied botanists.

The houlle (_Parkia biglobosa_) is a large tree from 35 to 50 feet in height, with a gray bark, many branches, and large, elegant leaves. The latter are compound, bipinnate (Fig. 7), and have fifty pairs of leaflets, which are linear and obtuse and of a grayish green. The inflorescence is very pleasing to the eye. The flowers, say the authors of the _Floræ Senegambiæ Tentamen_, form balls of a dazzling red, contracted at the base, and resembling the pompons of our grenadiers (Fig. 8). The support of this latter consists only of male flowers. The fruit that succeeds these flowers is supported by a club-shaped receptacle. It consists of a large pod, which at maturity is 13 inches in length by 10 in width (Fig. 1). This pod is chocolate brown, quite smooth or slightly tubercular, and is swollen at the points where the seeds are situated. The pods are straight or slightly curved. The aborigines of Rio Nunez use the pods for poisoning the fishes that abound in the watercourses. We do not know what the nature of the toxic principle is that is contained in these hard pods, but we well know the nature of the yellowish pulp and of the seeds that entirely fill the pods.

Although the pulp forms a continuous whole, each seed easily separates from the following and carries with it a part of the pulp that surrounds it and that constitutes an independent mass (Fig. 2). This pulpy substance, formed entirely of oval cells filled with aleurone, consists of two distinct layers. The first, an external one of a beautiful yellow, is from 10 to 15 times bulkier than the internal one, which likewise is of a beautiful yellow.

It detaches itself easily from the seed, while the internal layer, which adheres firmly to the exterior of the seed, can be detached only by maceration in water. This fresh pulp has a sweet and agreeable although slightly insipid taste. Upon growing old and becoming dry, it takes on a still more agreeable taste, for it preserves its sweetness and gets a perfume like that of the violet.

As for the seed, which is of a brown color and provided with a hard, shining skin, that is 0.4 inch long, 0.3 inch wide, and 0.2 inch thick. It is oval in form, with quite a prominent beak at the hilum (Fig. 4). The margin is blunt and the two convex sides are provided in the center with a gibbosity limited by a line parallel with the margin, and this has given the plant its specific name of _biglobosa_. The mean weight of each seed is 4½ grains. The skin, though thick, is not very strong. It consists, anatomically, of four layers (Fig. 5) of a thick cuticle, _c_; of a zone of palissade cells, _z p_; of a zone of cells with thick tangential walls arranged in a single row; and of a zone tougher than the others, formed of numerous cells with thick walls, without definite form, and filled with a blackish red coloring matter, _cs_. This perisperm covers an exalbuminous embryo formed almost entirely of two thick, greenish yellow cotyledons having a strong taste of legumine.

When examined under the microscope, these cotyledons, the alimentary part of the seed, have the appearance represented in Fig. 6, where _ep_ is the epidermic layer and _cp_ constitutes the uniform parenchyma of the cotyledonary leaf. This parenchymatous mass consists of oval cells filled with fatty matter and granules of aleurone.

According to some chemical researches made by Professor Schlagdenhauffen, the pulp has the following composition per 100 parts:

Fatty matter 2.407 Glucose 33.92 Inverted sugar 7.825 Coloring matter and free acids 1.300 Albuminous matter 5.240 Gummy matter 19.109 Cellulose 8.921 Lignose 17.195 Salts 4.080 ------- Total 100.000

The salient point of these analytical results is the enormous quantity of matter (nearly 60 per cent.) formed almost exclusively by sugar. It is not surprising, from this that this product constitutes a food both agreeable and useful.

An analysis of the entire seed, made by the same chemist, has given the following results:

Solid fatty matter 21.145 Unreduced sugar 6.183 Undetermined matters 5.510 Gummy " 10.272 Albuminoid " 24.626 Cellulosic " 5.752 Lignose and losses 20.978 Salts 5.534 ------- Total 100.000

The presence in these seeds of a large quantity of fatty matters and sugar, and especially of albuminoid matters (very nutritive), largely justifies the use made of them as a food. The innate instinct of the savage peoples of Africa has thus anticipated the data of science.--_La Nature._

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THE HEIGHT OF SUMMER CLOUDS.

A knowledge of the heights and movements of the clouds is of much interest to science, and of especial importance in the prediction of weather. The subject has therefore received much attention during recent years from meteorologists, chiefly in this country and in Sweden. In the last published report of the Meteorological Council for 1885-86 will be found an account of the steps taken by that body to obtain cloud photographs; and in the _Meteorologische Zeitschrift_ for March last, M.M. Ekholm and Hagstrom have published an interesting summary of the results of observations made at Upsala during the summers of 1884-85. They determined the parallax of the clouds by angular measurements made from two stations at the extremities of a base of convenient length and having telephonic connection. The instruments used were altazimuths, constructed under the direction of Prof. Mohn, specially for measuring the parallax of the aurora borealis. A full description of these instruments and of the calculations will be found in the _Acta Reg Soc. Sc. Ups._, 1884. The results now in question are based upon nearly 1,500 measurements of _heights_; the _motions_ will form the subject of a future paper. It was found that clouds are formed at all levels, but that they occur most frequently at certain elevations or stages. The following are, approximately, the mean heights, in feet, of the principal forms: Stratus, 2,000; nimbus, 5,000; cumulus (base) 4,500, (summit) 6,000; cumulo-stratus (base), 4,600; "false-cirrus" (a form which often accompanies the cumulo-stratus), 12,800; cirro cumulus, 21,000; cirrus, 29,000 (the highest being 41,000). The maximum of cloud frequency was found to be at levels of 2,300 and 5,500 feet.

Generally speaking, all the forms of cloud have a tendency to rise during the course of the day; the change, excepting for the cumulus form, amounting to nearly 6,500 feet. In the morning, when the cirrus clouds are at their lowest level, the frequency of their lowest forms--the cirro-cumulus--is greatest; and in the evening, when the height of the cirrus is greatest, the frequency of its highest forms--the cirro-stratus--is also greatest. With regard to the connection between the character of the weather and the height of the clouds, the heights of the bases of the cumulus are nearly constant in all conditions. The summits, however, are lowest in the vicinity of a barometric maximum. They increase in the region of a depression, and attain their greatest height in thunderstorms, the thickness of the cumulo stratus stretching sometimes for several miles. The highest forms of clouds appear to float at their lowest levels in the region of a depression. The forms of clouds are identical in all parts of the world, as has been shown in papers lately read by the Hon. R. Abercromby before the English and Scottish Meteorological Societies.--_Nature_.

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ON THE CAUSE OF IRIDESCENCE IN CLOUDS.

By G. JOHNSTONE STONEY.

When the sky is occupied by light cirro-cumulus cloud, an optical phenomenon of the most delicate beauty sometimes presents itself, in which the borders of the clouds and their lighter portions are suffused with soft shades of color like those of mother-of-pearl, among which lovely pinks and greens are the most conspicuous. Usually these colors are distributed in irregular patches, just as in mother-of-pearl; but occasionally they are seen to form round the denser patches of cloud a regular colored fringe, in which the several tints are arranged in stripes following the sinuosities of the outline of the cloud.

I cannot find in any of the books an explanation of this beautiful spectacle, all the more pleasing because it generally presents itself in delightful summer weather. It is not mentioned in the part of Moigno's great _Repertoire d'Optique_ which treats of meteorological optics, nor in any other work which I have consulted. It seems desirable, therefore, to make an attempt to search out what appears to be its explanation.

At the elevation in our atmosphere at which these delicate clouds are formed the temperature is too low, even in midsummer, for water to exist in the liquid state; and accordingly, the attenuated vapor from which they were condensed passed at once into a solid form. They consist, in fact, of tiny crystals of ice, not of little drops of water. If the precipitation has been hasty, the crystals will, though all small, be of many sizes jumbled together, and in that case the beautiful optical phenomenon with which we are now dealing will not occur. But if the opposite conditions prevail (which they do on rare occasions), if the vapor had been evenly distributed, and if the precipitation took place slowly, then will the crystals in any one neighborhood be little ice crystals of nearly the same form and size, and from one neighborhood to another they will differ chiefly in number and size, owing to the process having gone on longer or taken place somewhat faster, or through a greater depth, in some neighborhoods than others. This will give rise to the patched appearance of the clouds which prevails when this phenomenon presents itself. It also causes the tiny crystals, of which the cloud consists, to grow larger in some places than others.

Captain Scoresby, in his "Account of the Arctic Regions," gives the best description of snow crystals formed at low temperatures with which I am acquainted. From his observations it appears--(a) that when formed at temperatures several degrees below the freezing point, the crystals, whether simple or compound, are nearly all of symmetrical forms; (b) that thin tabular crystals are extremely numerous, consisting either of simple transverse slices of the fundamental hexagon or, more frequently, of aggregations of these attached edgewise and lying in one plane; and (c) that, according as atmospheric conditions vary, one form of crystal or another largely preponderates. A fuller account of these most significant observations is given in the appendix to this paper.

Let us then consider the crystals in any one neighborhood in the sky, where the conditions that prevail are such as to produce lamellar crystals of nearly the same thickness. The tabular plates are subsiding through the atmosphere--in fact, falling toward the earth. And although their descent is very slow, owing to their minute size, the resistance of the air will act upon them as it does upon a falling feather. It will cause them, if disturbed, to oscillate before they settle into that horizontal position which flat plates finally assume when falling through quiescent air. We shall presently consider what the conditions must be, in order that the crystals may be liable to be now and then disturbed from the horizontal position. If this occasionally happens, the crystals will keep fluttering, and at any one moment some of them will be turned so as to reflect a ray from the sun to the eye of the observer from the flat surface of the crystal which is next him. Now, if the conditions are such as to produce crystals which are plates with parallel faces, and as they are also transparent, part only of the sun's ray that reaches the front face of the crystal will be reflected from it; the rest will enter the crystal, and, falling on the parallel surface behind, a portion will be there reflected, and passing out through the front face, will also reach the eye of the observer.

These two portions of the ray--that reflected from the front face and that reflected from the back--are precisely in the condition in which they can interfere with one another, so as to produce the splendid colors with which we are familiar in soap bubbles. If the crystals are of diverse thicknesses, the colors from the individual crystals will be different, and the mixture of them all will produce merely white light; but if all are nearly of the same thickness, they will transmit the same color toward the observer, who will accordingly see this color in the part of the cloud occupied by these crystals. The color will, of course, not be undiluted; for other crystals will send forward white light, and this, blended with the colored light, will produce delicate shades in cases where the corresponding colors of a soap bubble would be vivid.

We have now only to explain how it happens that on very rare occasions the colors, instead of lying in irregular patches, form definite fringes round the borders of the cloudlets. The circumstances that give rise to this special form of the phenomenon appear to be the following: While the cloud is in the process of growth (that is, so long as the precipitation of vapor into the crystalline state continues to take place), so long will the crystals keep augmenting. If, then, a cloudlet is in the process of formation, not only by the springing up of fresh crystals around, but also by the continued growth of the crystals within it, then will that patch of cloud consist of crystals which are largest in its central part, and gradually smaller as their situation approaches the outside. Here, then, are conditions which will produce one color round the margin of the cloud, and that color mixed with others, and so giving rise to other tints, farther in. In this way there comes into existence that iris-like border which is now and then seen.

The occasional upsetting of the crystals, which is required to keep them fluttering, may be produced in any of three ways. The cloudlets may have been formed from the blending together of two layers of air saturated at different temperatures, and moving with different velocities or in different directions. Where these currents intermix, a certain amount of disturbance will prevail, which, if sufficiently slight, would not much interfere with the regularity of the crystals, and might yet be sufficient to occasion little draughts, which would blow them about when formed. Or, if the cold layer is above, and if it is in a sufficient degree colder, there need not be any previous relative motion of the two layers; the inevitable convection currents will suffice. Another, and probably the most frequent, cause for little breezes in the neighborhood of the cloudlets is that when the cloudlets are formed they immediately absorb the heat of the sun in a way that the previously clear air had not done. If they absorb enough, they will rise like feeble balloons, and slight return currents will travel downward round their margins, throwing all crystals in that situation into disorder.

I do not include among the causes which may agitate the crystals another cause which must produce excessively slight currents of air, namely, that arising from the subsidence of the cloudlets owing to their weight. The crystals will fall faster wherein cloud masses than in the intervening portions where the cloud is thinner. But the subsidence itself is so slow that any relative motions to which differences in the rate of subsidence can give rise are probably too feeble to produce an appreciable effect. Of course, in general, more than one of the above causes will concur; and it is the resultant of the effects which they would have separately produced that will be felt by the crystals.

If the precipitation had taken place so very evenly over the sky that there were no cloudlets formed, but only one uniform veil of haze, then the currents which would flutter the crystals may be so entirely absent that the little plates of crystals can fixedly assume the horizontal position which is natural to them. In this event the cloud will exhibit no iridescence, but, instead of it, a vertical circle through the sun will present itself. This, on some rare occasions, is a feature of the phenomenon of parhelia.

It thus appears that the occasional iridescence of cirrus clouds is satisfactorily accounted for by the concurrence of conditions, each of which is known to have a real existence in nature....--_Phil. Mag., July 1887._

* * * * *

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