quarter in which he observed them advancing. The same watchman was obliged, likewise, to blow his horn on an alarm of fire; and that these people might be vigilant day and night, both in winter and summer, the council supplied them with fur-cloaks, seven of which, in the above-mentioned year, were purchased for ten florins and a half.

In the year 1496, the large clock was put up in the steeple of Oettingen, and a person appointed to keep watch on it In 1580, Montagne was much surprised to find on the steeple at Constance a man who kept watch there continually; and who, on no account, was permitted to come down from his station.

[One of the greatest improvements of modern times, in this country, is the establishment of that highly efficient body, the new police. The first introduction of the police was made by the magistrates of Cheshire in 1829, under an authority from parliament (Act 10 Geo. IV. c. 97). The first metropolitan establishment was also made in 1829. Before this time the total old force of the metropolitan watchmen consisted of 797 parochial day officers, 2785 night-watch, and upward of 100 private watchmen; including the Bow-street day and night patrol, there were about 4000 men employed in the district stretching from Brentford Bridge on the west to the river Lea on the east, and from Highgate on the north to Streatham on the south, excluding the city of London. The act of parliament creating the new police force (10 Geo. IV. c. 44) placed the control of the whole body in the hands of two commissioners, who devote their whole time to their duties. The total number of the metropolitan police in January 1840 consisted of 3486 men. These are arranged in divisions, each of which is employed in a distinct district. The metropolis is divided into "beats" and is watched day and night. Since August 1839, the horse-patrol, consisting of seventy-one mounted men, who are employed within a distance of several miles around London, has been incorporated with the metropolitan police. The Thames police consists of

1 This is related in the Oettingisches Geschichts-almanach, p. 7, on the authority of an account in the parish books of Oettingen, said to be ex tracted from an ancient chronicle of that town. The author of this al manac, which is now little known, was, as I have been told, Schablen, superintendant at Oettingen.

twenty-one surveyors, each of whom has charge of three men and a boat when on duty. The establishment is under the immediate direction of the magistrates of the Thames policeoffice.

The police affairs of the city of London are still under its own management. In 1833, the number of persons employed in the several wards of the city was,-ordinary watchmen, 500; superintending watchmen, 65; patrolling watchmen, 91; beadles, 54; total, 710. There are about 400 men doing duty in the city at midnight. In addition to the paid watchmen, about 400 ward-constables are appointed. The expense of the day-police, consisting of about 120 men. amounts to about £9000 a year, and is defrayed by the corporation: and the sum levied on the wards for the support of the nightwatch averages about £42,000 per annum.

The police of the metropolis and the district within fifteen miles of Charing Cross (exclusive of the city) is regulated by the acts 10 Geo. IV. c. 44, and 2 and 3 Vict. c 47. In nearly all the boroughs constituted under the Municipal Reform Act, a paid police force has been established on the same footing as the metropolitan police.]

PLANT-SKELETONS.

PLANTS, as well as animals, are organised bodies, and like them their parts inay be dissected and decomposed by art; but the anatomy of the former has not been cultivated so long and with so much zeal and success as that of animals. Some naturalists, about the beginning of the last century, first began to make it an object of attention, to compare the structure of plants with that of animals; and for that purpose to employ the microscope. Among these, two distinguished themselves in a particular manner; Marcellus Malpighi, an Italian; and Nehemiah Grew, an Englishman; who both undertook almost the same experiments and made them known at the same time: so that it is impossible to deter

mine which of them was the earlier. It appears, however, that Grew published some of his observations a little sooner; but Malpighi was prior in making his known in a complete manner. But even allowing that the one had received hints of the processes of the other, they are both entitled to praise that each made experiments of his own, and from these prepared figures, which are always more correct the nearer they correspond with each other.

Among the various helps towards acquiring a knowledge of the anatomy of plants, one of the principal is the art of reducing to skeletons leaves, fruit and roots; that is, of freeing them from their soft, tender and pulpy substance, in such a manner, that one can survey alone their internal, harder vessels in their entire connexion. This may be done by exposing the leaves to decay for some time soaked in water, by which means the softer parts will be dissolved, or at least separated from the internal harder parts, so that one, by carefully wiping, pressing and rinsing them, can obtain the latter alone perfectly entire. One will possess then a tissue composed of innumerable woody threads or filaments, which, in a multiplicity of ways, run through and intersect each other. By sufficient practice and caution one may detach, from each side of a leaf, a very thin covering, between which lies a delicate web of exceedingly tender vessels. These form a woody net-work, between the meshes of which fine glandules are distributed. This net is double, or at least can be divided lengthwise into halves, between which may be observed a substance that appears as it were to be the marrow of the plant. Persons who are expert often succeed so far, with many leaves, as to separate the external covering on both sides from the woody net, and to split the latter into two, so that the whole leaf seems to be divided into four.

One might conjecture that this method of reducing leaves to skeletons must have been long known, as one frequently finds in ponds leaves which have dropped from the neighbouring trees, and which by decomposition, without the assistance of art, have been converted into such a woody network, quite perfect and entire. It is however certain that a naturalist, about the year 1645, first conceived the idea of employing decomposition for the purpose of making leafskeletons, and of assisting it by ingenious operations of art.

This naturalist, Marcus Aurelius Severinus, professor of anatomy and surgery at Naples, was born in 1580, and died of the plague in 1656. In his Zootomia Democritæa, printed in 1645, he gave the figure, with a description of a leaf of the Ficus Opuntia reduced to a skeleton. Of the particular process employed to prepare this leaf, the figure of which is very coarse and indistinct, he gives no account. He says only that the soft substance was so dissolved that the vessels or nerves alone remained; and that he had been equally successful with a leaf of the palm-tree. A piece of a leaf of the like kind he sent by Thomas Bartholin to Olaus Wormius, who caused it to be engraved on copper, in a much neater manner, without saying anything of the method in which it had been prepared'. The process Severin kept secret; but he communicated it to Bartholin, in a letter, on the 25th of February 1645, on condition that he would not disclose it to any one. At that period, however, it excited very little attention, and was soon forgotten, though in the year 1685 one Gabriel Clauder made known that he had reduced vine-leaves, the calyx of the winter cherry, and a root of hemlock, to a net or tissue by burying them in sand during the heat of summer, and hanging them up some months in the open air till they were completely dried.

This art was considered to be of much more importance when it was again revived by the well-known Dutchman, Frederick Ruysch. That naturalist found means to conduct all his undertakings and labours in such a manner as to excite great wonder; but we must allow him the merit of having brought the greater part of them to a degree of perfection which no one had attained before. By the anatomy of animals, in which he was eminently skilled, he was led to the dissection of plants; and as it seemed impossible to fill their tender vessels, like those of animals, with a coloured solid substance, he fell upon a method of separating the hard parts from the soft, and of preserving them in that manner.

' Museum Wormianum. Lugd. Bat. 1655, fol. p. 149.

2 The well-known Sir John Hill, an Englishman, has proved, however, in later times, the possibility of injecting a substance into the vessels of plants also. He dissolved sugar of lead in water, suspended in it bits of the finest wood, so that one-half of them was under water and the other above it, and covered the vessel in which they were placed with an in

For this purpose he first tried a method which he had employed with uncommon success, in regard to the parts of ani→ mals. He covered the leaves and fruit with insects, which ate up the soft or pulpy parts, and left only those that were hard. But however well these insects, which he called his little assistants, may have executed their task, they did not abstain altogether from the solid parts, so that they never produced a complete skeleton. He dismissed them, there fore, and endeavoured to execute with his own fingers what he had before caused the insects to perform, after he had separated the soft parts from the hard by decomposition. In this he succeeded so perfectly, that all who saw his skeletons of leaves or fruit were astonished at the fineness of the work and wished to imitate them.

I cannot exactly determine the year in which Ruysch began to prepare these skeletons. Trew thinks that it must have been when he was in a very advanced age, or at any rate after the year 1718; for when he was admitted to Ruysch's collection in that year, he observed none of these curiosities. Rundmann, however, saw some of them in his possession in the year 1708'. At first Ruysch endeavoured to keep the process a secret, and to evade giving direct answers to the questions of the curious. We are informed by Rundmann, that he attempted to imitate his art by burying leaves at the end of harvest in the earth, and leaving them there till the spring, by which their soft parts became so tender that he could strip them off with the greatest ease. He produced also the same effect by boiling them.

The first account which Ruysch himself published of his process, was, as far as I know, in the year 1723. After he had sufficiently excited the general curiosity, he gave figures of some of his vegetable skeletons, related the whole method of preparing them, and acknowledged that he had accidentally met with an imperfect engraving of a leaf-skeleton in the Muverted glass. At the end of two days he took the bits of wood out, cut off the parts which had been immersed in the water, dipped them in a warm lye made of unslaked lime and orpiment, like what was used formerly for proving wine; and by these means the finest vessels, which had been before filled with sugar of lead, acquired a dark colour, and their apertures became much more distinct. This process he describes himself in his work on the Construction of Timber.

Rariora Naturæ et Artis. Breslau and Leipsic, 1737, fol. p. 421.