lime and sand mortar, prepared in the most careful manner, will never acquire hardness under water, and should therefore be avoided in such situations.

The works began on the 4th of August, 1824—the first stone was laid on the 16th of March, 1825, and the bridge was opened on the 14th of July, 1827-on which day her Royal Highness the Duchess of Clarence and suite first passed over it.*

The foundations, masonry &c. of the bridge, were executed under contract by Messrs. Johnson, of the Plymouth Granite works, and of Holywell-street, London; the manner in which the work is finished, is their best praise. The iron superstructure is by that able and experienced founder, Mr. Hazledine, of Shrewsbury.

It is needless here to eulogize the public spirit evinced by the Earl of Morley in this important work; the expense of which was certain and considerable, whilst its returns could only be precarious. For the steady confidence with which

The following inscription which was furnished by Mr.Waller, and approved and amended by the late Right Honourable George Canning, Mr. William Bankes, the Earl of Carlisle, the Rev. Charles Young, and other scholars of eminence, is affixed to a block of granite, at the northern extremity of the bridge.

HUNC PONTEM

SENATUS AUCTORITATE SUSCEPTUM

NOVAS ET COMMODAS VIAS

RECLUDENTEM

JOHANNES COMES DE MORLEY,

SUIS SUMPTIBUS

STRUENDUM CURAVIT.

OPUS INCHOATUM, A. D. 1824;

ABSOLUTUM, A. D. 1827.

J. M. RENDEL, ARCHITECTO.

his Lordship encouraged one, young both in years and in his profession, to meet and surmount the various obstacles and natural difficulties in the execution of this work, personal gratitude alone is due-but for the advantages derived from the bridge itself, the Earl of Morley has laid the public of Plymouth under lasting obligation.

The benefits to a nation, from such a spirit of truly patriotic liberality amongst her nobility, are incalculable. To the many magnificent exertions of it, England owes no small part of her commercial prosperity; and the names of the Dukes of Bridgewater, of Portland, &c. &c. should be venerated by every lover of his country, as powerful contributors to its present eminence. With regard to Plymouth, it is to be hoped that the example set by the noble Earl in this and other public works in the vicinity, may find imitators. The natural advantages of the town and port are great, and nothing appears to be wanting for raising them to a still higher scale of national importance, but a continuance of that enterprising and liberal spirit which is at present dawning amongst a large portion of the inhabitants.

Plymouth, Jan. 1829.

IV.

ON THE RISE AND DECLINE OF PARTICULAR MORTAL DISEASES, DURING THE LAST TWENTY-FIVE YEARS; WITH AN ATTEMPT TO ASCERTAIN THE LAW OF MORTALITY, IN RESPECT OF ITS DISTRIBUTION ON VARIOUS AGES, AND IN BOTH SEXES: BY EDWARD BLACKMORE, M. D. MEMBER OF THE ROYAL MEDICAL SOCIETY OF EDINBURGH, AND OF THE PLYMOUTH INSTITUTION.

Duntaxat Rerum Magnarum parva potest res
Exemplare dare, ac vestigia notitiai.

LUCRETIUS.

THE subject of this paper is contained in the following passage of MALTHUS's Essay on the Principle of Population, vol. 2, B. iv. c. 5.—“ Nature will not be defeated in her purposes; the necessary mortality must come in some form or other; and the extirpation of one disease will only be the signal for the birth of another, perhaps more fatal. We can

not lower the waters of misery by pressing them down in different places, which must necessarily make them rise somewhere else the only way in which we can hope to effect our purpose, is by drawing them off. In a country which keeps its population at a certain standard, if the average number of marriages and births be given, it is evident that the average number of deaths will be also given; and the channel through which the great stream of mortality is constantly flowing, will

always carry off a given quantity. Now if we stop up any of the given channels, it is most perfectly clear that the stream must run with greater force through some of the other channels; that is, if we eradicate some diseases, others will become more fatal. In this case, the only distinguishable cause is the damming up a necessary outlet of mortality. The way in which it operates, is probably by increasing poverty, in consequence of a supply of labour too rapid for the demand. If the cowpock should extirpate the small-pox, and yet the number of marriages continue the same, we shall find a very perceptible difference in the increased mortality of some other disease. Nothing could prevent this but a start in agriculture."The view of the reign of death herein exhibited, is truly dark and startling. This doctrine of the constancy of mortality wears an aspect which is naturally calculated to repress the efforts of philanthrophists to extirpate diseases;—and the fatalism with which it invests mortality, tends to shut up mankind in hopeless subjection to the various ills of their condition. The passage moreover assumes, that mortal diseases will necessarily and perpetually exist; and thus for ever precludes the hope of man's attaining to a natural issue of his earthly existence in the exhaustion of mature old age.Omitting to discuss the truth of this proposition in the abstract, as designating the law of mortality in a state of society where the population is making pressure on the means of subsistence, I propose to inquire-How far, from the register of deaths in the course of the last twenty-five years, mortality is shewn to be a constant quantity?—What changes have been wrought in the various channels through which the great stream of mortality has been flowing-What relative proportion is observable in the rise and fall of particular diseases?— Has, for example, the depression in the mortality of the SMALLPOX since the discovery of the cow-POCK, been a means of diminishing the general mortality in the rate of that depression; or, has an increase in the mortality of some other diseases, absorbed those whom the decline of the small-pox had permitted