bearing blossom, which is the rudiment | endeavour to understand what is here of a berry both are magnified. : To the twenty-third class, Polygamia, belong those plants whose flowers seem to be subject to no law of regularity, in the arrangement of the stamens and pistils. In some of the flowers are stamens only, in others pistils only, in others both stamens and pistils, (fig. 23.) Fig. 23. laid before you, by making it, as far as is practicable, matter of experiment. You may find even at this season of the year, when winter still lingers with us, many objects in the vegetable kingdom adapted to excite your admiration, in whatever direction you may feel disposed to rusticate; but the walk most prolific in objects of botanical nature will be along a lane, where the elevated hedgebank luxuriates in the morning sun. You should provide yourself with a tin botanizing box of convenient size, in which, if you have a garden for transplanting, you may carry a garden trowel. Thus equipped-and of such an accompaniment no one need be ashamed-you set out for your ramble, whether it be for The twenty-fourth class, Cryptoga-be either to find the locality of some paran hour, or for more; your object may mia, contains that branch of vegetation, ticular plant, or to fill a budget of whatwhose reproductive organs are undefined or indistinct, as the term implies. Fungi which you may bring home, and at leisure ever may be to you new and unexplored, or mushrooms, moss of all varieties, ferns, sea-weeds, lichens, &c., belong the most despised leaf, or insignificant investigate. And you may be assured that morsel of moss, or a single bud of a tree, will amply reward the most diligent scrutiny. You will find a pocket lens to to it. Now that the student may be able to determine to what class any plant belongs, let him pursue the following course. First, ascertain whether it has a simple or a compound flower: by the term compound, applied to a flower, is meant one that belongs to the class, Syngenesia. If simple, whether both stamens and pistils are present in every flower; if they are not, it will belong either to 21, 22, or 23. If in every flower there are present both stamens and pistils, observe whether the stamens are united into one or more sets; if so, it will belong either to 16, 17, or 18. If they are not united, nor are produced upon the pistil, count them, bearing in mind the difference between 12 and 13, 4 and 14, 6 and 15. This process is simple enough, and cannot fail of conducting to a correct result. The substance of this paper well considered, as it may be in a few hours, the student has made an important acquisition, and may cheerfully proceed, assured that he is going an easy way to obtain rational pleasure and improvement. In the next paper we purpose illustrating the first subdivision of this tem, called the Orders. In the meantime, kind reader, if you are disposed to view nature with an intelligent eye, and if you deem the present attempt in any measure calculated to assist you, sys be very serviceable in your examinations of the minute parts of the flower, &c., if you should not be fortunate enough to possess a proper botanical microscope. Such researches, besides the immediate pleasure they will impart to the student, will greatly assist his subsequent progress. flower in the course of this month :The following plants will probably CLASS DIANDRIA. *B.. Veronica agrestis, wall speedwell. TRIANDRIA. B. Crocus, of different varieties. HEXANDRIA.-B. Galanthus nivalis, the snowdrop. OCTANDRIA.—B. Daphne Mezereon, the mezereum. POLYANDRIA.— G. Helleborus niger, the Christmas rose. G.Helleborus hyemalis, the Winter aconite. G.Hepatica triloba, white, red, and blue. DIDYNAMIA.-B. Lamium album, white dead nettle. B.Lamium purpureum, purple do. TETRADYNAMIA.-B.Draba verna, early whitlow grass, grows on old walls. DIADELPHIA.-B. Ulex Europæus, the common furze or gorse. SYNGENESIA. B.Senecio vulgaris, the common groundsel. B. Bellis perennis, the daisy.B, Tussilago petasites, the white butter bur. The investigation of these, and whatever may ocur in the class Cryptogamia, will afford abundant employment for the present month to the lover of botany. B. British or wild. ↑ G. grows in gardens. ELECTRICITY FROM MAGNETS. Ir is commonly supposed that electricity resides in all substances, each kind of matter having it in a fixed amount, and in a particular condition. When thus united with material existence, as a necessary element, it is, in reference to all our sensations, latent; and if it had not been separated from the matter with which it is combined, we could not possibly have been acquainted with its existence. We may illustrate our remarks on this subject by a comparison of electricity and heat. When we place a liquid over the fire, and expose it to a temperature greater than its own, the effect produced is soon made evident to the sense of touch. When the finger is plunged into a liquid thus acted upon by heat, we become conscious of a different state, and are accustomed to say, that its temperature has increased, or, in other words, that it is hotter. This is an effect produced, when heat is acting as a free agent; but there are times when it is so intimately connected with matter as to be altogether incapable of affecting the sense of touch, and is then said to be latent. Thus a vapour or a gas possesses a certain amount of heat necessary to support its condition, the removal of which will, in fact, change its state. Let us take steam as an example. Steam is formed by the addition of heat to water at the boiling point, that is 212 degrees. Under the common pressure of the atmosphere, water cannot be raised to a temperature greater than 212 degrees, and yet heat may be communicated to the liquid long after this has been done, and must produce some effect. Every one knows that it causes the formation of steam. But the steam is not hotter than the water, so that the heat must be in some manner connected with the particles of water in a latent state. For a further explanation of this subject, the reader may refer to a paper on "The Tea-kettle," Visitor, 1837, p. 91. Now, electricity exists in all substances in this latent state, but may be disturbed or set free in various ways, and it is only then that we can acquire any knowledge of its properties and effects. When two substances are rubbed together, their electric condition is disturbed. This means of obtaining free electricity was first discovered; and the agent thus developed is called common or ordinary electricity. For many years scientific men were experimenting with the elec trical machine without suspecting that any other means of obtaining the agent could be found. It was, however, discovered accidentally, that by the contact of metals and chemical action, the same agent was developed, producing effects sufficiently analogous to those of the common electricity to identify it as the same agent, yet vastly superior in many respects in its powerful control over matter. In the year 1824, Seebech discovered that when a circuit of perfect metallic conductors is formed, and unequally heated, the electrical condition is disturbed. This effect does not depend on any peculiarity in the metals, their contact or juncture. In the same year Yelin succeeded in an attempt to obtain electricity from a single metal. From his experiments it appears that electricity may be obtained from any metallic substance, when unequally heated. To distinguish the agent derived from this source, it is called thermo-electricity. Another and a fourth source of electricity has long been known; we refer to the electrical fishes. It appears that certain fishes are furnished with organs by which they are able to accumulate and discharge electricity. Such is the power of some of them in this respect, that it would be unsafe to receive a discharge from a full-grown and active fish. (See Weekly Visitor, for 1834, p. 447, 455.) We come now to the fifth source of electricity, and that which is the immediate object of our attention in this paper. Many of our readers are aware that electrical effects have been obtained from magnets. A large apparatus has been long exhibited in the Gallery of Practical Sciences, by which many curious experiments were shown. This arrangement, however, has been superseded by one invented by Mr. Clarke, the philosophical instrument maker. But before we proceed to a description of this instrument, and the experiments which may be performed with it, a few remarks will be required upon the means by which we may identify the electric agent. The effects obtained by the rotation of the armature of a magnet, forming and breaking contact with the poles, has been called magneto-electricity. How do we know that electricity is the cause? To this question we reply, because it produces results similar to those obtained from that agent, in whatever manner it may be developed. The effects of elec F To decompose water. Water is a compound substance, formed of the two gases, oxygen and hydrogen. By electricity it may be decomposed, resolved, in fact, into its two elements. The gases may be either collected together in one tube, or separately, in a tube provided for each. Fig. 2 is a representation of B FIG.2 evolve heat, and to render soft iron | shock as soon as the multiplying wheel magnetic, quantity must be obtained. is turned. u and v are directors, used The inventor of this machine has pro- for applying magneto-electricity medivided an arrangement, by which both cinally. may be obtained by two different armatures; one he calls the intensity, and the other the quantity armature. The former has two coils of fine insulated copper wire, 15,000 yards long, bound round its cylinder, the latter only forty: so, also, the amount of iron employed in the construction of the cylinders, is smaller in the intensity than in the quantity armatures; but the connexion of the wires is the same in both. The commencement of each coil of copper wire is soldered to the armature D, from which projects a brass stem, (also soldered into D,) carrying the breakpiece H. The break-piece н is made fast in whatever position is required, by a small binding-screw. K is a hollow brass cylinder, to which the termination of the coils F G are soldered, being insulated by a piece of hard wood attached to the brass stem. o is an iron wire spring pressing against the hollow cylinder K at one end, and held in metallic contact by a nurled head-screw in the brass strap м, which is fixed to the wooden block L. P is a square brass pillar, fitting into a square opening in the other brass strap N, and secured at any convenient height required. q is a metal spring that rubs gently on the break-piece н, and is held in perfect metallic contact by the nurled ́headscrew in P. T is a piece of copper wire for connecting the two brass straps M N; then D, H, Q, P, N, are in connexion with the commencements of each coil, and K, O, м, with the terminations. M H the apparatus for the collection of the gases in one tube. A is a glass cup, The latter part of this description we with a wooden bottom, through which have given as an extract from the in- two pieces of copper wire with platina ventor's explanation of his machine in points are passed. The tube B being the Annals of Electricity. We may filled with water, and the vessel partly now proceed to explain one or two ex-filled, the open end of the tube is placed periments which may be made with the intensity armature. To give a shock. R and s, fig.1, are brass conductors. The end of the wire connected with one of these is placed in the hole of one of the brass slips м or N, and the wire of the other into a hole that is formed at the end of the brass stem, which carries the break н. M and N are united by a wire T. If the person to receive the shock, take hold of the brass cylinders R in one hand, and s in the other, he will experience a violent over the platina wires, in which position it will be supported by the cork c, and the copper wires with which they are connected are fixed in the points м and N. The spring a must then be so fixed as to rub on the cylindrical part of the break, and as soon as the wheel is turned the gases will begin to rise, and will soon entirely fill the tube, driving the water into the glass vessel. The Fig. 3 represents the apparatus used to collect the gases separately. glass vessel is similar in construction to that already described, except that the | the points м and N are soldered to the copper wires, instead of terminating in two brass cups b b. Into these cups To scintillate iron wire. Brilliant | chine. An iron wire, A, is connected at scintillations of iron wire may be easily one end with an upright, (P, fig. 1.,) as produced with the magneto-electric ma- shown in figure 4, the other end being FIG. 4 A D gently pressed on the surface of the rotating armature. The brilliant combustion thus produced is effected, we are informed by the inventor, in consequence of the wires being soldered to the armature. This fact is the more worthy of notice, because it was long supposed by those most acquainted with electrical phenomena, that the union of the wires and armature would entirely destroy the effect, instead of increasing it. |