electric matter collected in them, whilst those of the second class lose it as soon as they receive it*. Machines have been invented, in which, by means of a wheel, a rapid rotation is given to a glass globe, or cylinder, upon which is placed a cushion of silk, against which, whilst whirling round, it rubs. By this friction the globe preserves its electric virtue, which may be extended to any distance by means of metallic bars, or chains which communicate with the glass. If, while the machine is working, we touch the chain, we immediately receive a shock; and, if the room is darkened, a luminous spark will be perceived. Let any number of persons join hands and form a circle, and by means of the chain make a communication with the machine; and they will all receive a shock at the same time, which may be made more or less violent. The electric fluid may be accumulated to such a degree as to kill by its discharge the largest animals.

This experiment is performed with several glass jars nearly filled with water, aud which, connected together by chains, communicate with the glass globe before described. The water communicates to the internal surface of the jars a great quantity of electric matter, their external surface at the same time losing an equal quantity by means of its communication with some conducting body. A vivid flash, loud ex

* Those substances mentioned in the first class, to which may be added diamonds, balsamic and bituminous bodies, as amber, sulphur, &c. the coverings of animals, as feathers, wool, bristles, silk, vitrified bodies, and all substances that, when rubbed, attract light bodies, are called electrics or nonconductors. Those on the contrary in which, when friction is employed, the electric fluid is not excited or put in motion, are called conductors or non-electrics; and they consist chiefly of metals, minerals, aqueous and spirituous liquids, living creatures, and animal and vegetable substances, as trees, plants, bones, shells, &c.

plosion, and a violent agitation, ignition of combustible matter, and the death of the subject of the experiment, are the consequences of this experiment.

There are other effects which are common to all experiments of this kind; such as a sulphureous smell, an agitation in the air, a sudden flash, and the electric matter, acquiring a new property. Some experiments have failed because the metallic rods which served as conductors were too angular and pointed. It has been suspected that the electric fluid in such cases was dissipated by means of the points; and this was confirmed when on approaching the face or hand to the point of the rod, a copious stream of electric fluid emanated from them; it was also conjectured, that these points, which throw off the electric fluid, might attract it, and a number of experiments have since established it as a truth.

Electricity has been applied by physicians in many complaints with great success; and a still greater advantage which we derive from its investigation is the analogy which naturalists have discovered between electricity and lightning, which has given rise to new conjectures upon the nature of thunder; and has taught us to secure our buildings, by means of metallic rods, from the destruction they often suffer during a storm.

Thus we are continually receiving new solutions of the mysteries contained in the great works of nature; and from the success of these investigations we should be excited to more industry, and to pay greater attention to the works of the creation daily offered to our

view.

JUNE XXVI.

Manner in which Thunder is formed.

FORMERLY, and even to the beginning of the eighteenth century, it was commonly supposed that thunder was occasioned by the agitation of saline, sulphureous, and other substances contained in the air. It was imagined that there was the greatest resemblance between the effect of fire-arms and that of thunder and lightning. But all the means by which men endeavoured to explain and establish this system were not sufficient to do away the difficulties that presented themselves, nor to account for the fact. Since that period, however, the phenomena produced by the electric fluid have been more attentively observed, and a very different cause has been assigned to the formation of thunder. The great resemblance between it and electricity has convinced naturalists that they are produced by the same causes, and that electricity is in our hands what thunder is in nature. It will not be difficult to demonstrate this, even to those who are ignorant of natural philosophy, if they will only take the trouble to compare the effects of thunder with those of electricity.

The effects of thunder are known by peals heard at a greater or less distance, and by flashes of fire; buildings struck by it are often consumed by flames; men exposed to it become black, and appear scorched, though there is sometimes no trace of fire, the violence of the stroke having killed them: their clothes are torn, they are thrown to some distance from the place in which they were, and frequently the part of the body which was struck is pierced with holes. Sometimes large stones are broken by the thunder, and its ravages are easily discoverable on the ground where it strikes.

Electricity presents us with similar effects, but in a less degree. When by means of water its force is increased, the electric flash is followed by a very evident commotion: the most compact bodies are perforated, birds and other small animals are deprived of life, and each flash is succeeded by a report. The stream of fire also, which passes from the points of electrified bodies with a hissing noise, is one of the phenomena observable in lightning; and with respect to velocity, there is still greater resemblance between thunder and electricity. If during a storm a sword or chain is suspended in the air by silken strings, they become electrified; and if the finger is advanced near them, sparks proceed from them with more or less force and brilliancy, according to the violence of the storm, and the distance of the electric cloud; in short, every effect of electricity is produced during a thunder-storm. From all these circumstances, we can no longer doubt that the air during a storm is highly electric, and that thunder and lightning are merely the effects of a violent electric fire*.

Thus all that appears supernatural in these phenomena, and the terror that they consequently excite, will be done away as we become better acquainted with the laws of nature. This should induce every one to acquire at least the first principles of natural philosophy. We should then no longer see fear and superstition enervate the mind, and paralyze our exertions in the investigation of nature. Let us employ the little light we have to dispel the fear which

Lightning, then, is nothing more than the electric fluid contained in the clouds passing into other bodies, and thus interrupting the equilibrium, and producing concussions in the air, or that noise which we call thunder; and the reason that lightning is seen before the thunder is heard, is that light travels with a velocity inconceivably greater than sound. -E.

troubles us at the approach of a thunder-storm; and, amid the lightning's flash and the roaring of the tempests, we shall regard with a tranquil bosom the God of all, who "rides in the whirlwind and directs the storm." For however we may be able to assign the causes of thunder upon just and invariable principles, drawn from natural philosophy, the phenomena are not less remarkable, and present some circumstances which are inexplicable, even to the most enlightened mind. It is sufficient for us to know that the nature of the air, and the peculiar properties of the surrounding atmosphere, render this phenomenon necessary: that these storms are essential to the fertility of the earth, and should therefore excite us to render our tribute of praise and thanksgiving to the all-bountiful Creator.

JUNE XXVII.

Herrings.

In this season of the year the herring-fishery begins on the coasts of England and Scotland; by which we shall soon receive a great abundance of fish, which supply the inhabitants with food during a considerable part of the year. Let us examine what is most important in the natural history of these fish.

An innumerable multitude of herrings live in the Icy sea, near the arctic pole; at a certain time they quit this abode, and arrive in shoals upon the coasts of England and Holland. The cause of this emigration is not yet ascertained: some suppose it is to escape from the whale, and other great fish of the Icy sea; others imagine that the prodigious multiplication of herrings is the cause of their taking these long voyages; that finding themselves too numerous under the northern ice, they are obliged to detach colonies to other