subtraction, multiplication, and division. Although there is reason to believe that the apparatus which he formed was strictly of his own invention, yet it must be observed that he was not original in his idea of forming an arithmetical machine, and that the general principle of them must probably be nearly the same. It has been asserted, upon grave authority, that his Lordship conceived the possibility of forming a reasoning machine, by which the results of certain combinations of ideas, or of elementary propositions, might be ascertained with as much ease and accuracy as those of figures. But it is scarcely necessary to observe that, independent of other difficulties, no mecha nical process for reasoning can ever be employed until mankind have agreed upon certain general principles as decidedly as upon the value of certain numbers, and until all doubt has been removed respecting the import of words, or the combinations of them. A machine for resolving political queries would give very different answers, according as it was constructed under the superintendance of an advocate for reform, or an admirer of the infallible wisdom of our ancestors. Lord Stanhope is well known to have suggested some important improvements in the construction of the printing press, and to have been an early and active patron of the stereotype method of printing. He also wrote a scientific and ingenious essay on the method of tuning instruments; and invented a new system, which is considered as founded upon correct principles.

It is much to be lamented that, while Lord Stanhope was thus devoting his time and fortune to objects of real or supposed utility, and appeared to be guided by the purest philanthropy and the most honourable principles, either his natural disposition, or the circumstances of his life, produced a state of mind and conduct which deprived him of the endearments of domestic life, and even, in a considerable degree, of the consolations of friendship. His excessive zeal for politics, and the earnestness and good faith with which he embraced his own doctrines, seem to have rendered him incapable of supposing that those could be actuated by honourable motives who differed from him; and as it happened, unfortunately, that he was very nearly related to the family of Mr. Pitt, it led to a domestic schism, which eventually ended in the separation and estrangement of his own children. It appears, indeed, that Lord Stanhope possessed but a very small share, if any, of those amiable qualities which so essentially contribute to the real happiness of life, and which are poorly compensated by the more splendid endowments of learning or science, and cannot be superseded even by honour and integrity, Lord Stanhope died in December, 1816, in the 64th year of his age, exhibiting, in the last scene of his life, ant unusual degree of philosophical resignation. He has left behind him a character which demands our respect, and which will probably be more highly estimated by posterity than it was by his contemporaries. The man of candour will regret that

so much of what was valuable was obscured by what was repulsive, and the patriot will regret that so much public spirit and integrity was rendered useless by excessive zeal and undue attachment to speculative principles.

ARTICLE II.

Memoir on the Geographical Extent of the Strata of the Environs of Paris. By J. J. Omalius d'Halloy.*

THE learned examinations of MM. Cuvier and Brongniart have attracted the general attention to the strata of the environs of Paris. This is not to be wondered at, as they contain so great a quantity of the remains of organized beings that they present a vast field to the researches of true philosophical geology; which, drawing its conclusions from the knowledge of the organic remains buried in the earth, can alone give us certain means of comparing distant strata, and which will, perhaps, one day throw some light on the different catastrophes that have changed the surface of the globe, as it has already given indications of the nature of the liquids in which some of those phenomena have taken place.

The extent of the Paris basin, and the plan of MM. Cuvier and Brongniart, having prevented them from determining the whole of the limits of this district, I have thought that a detailed examination of those limits would be interesting, and I have undertaken several journeys for that purpose, of which I now offer the result. I should, however, observe, that a part of this labour has been already performed by M. Desmarest, sen.† who has carefully traced the limits of the chalk of Champagne. I have also derived much assistance from the mineralogical atlas of M. Monnet, and two memoirs of MM. de Tristan and Bigot de Morogues, for some other parts.

The different formations which compose the strata of the environs of Paris, considered in their mass, and without including some insulated portions, occupy a surface of about 174 square myriameters, in the form of an irregular polygon, longest in the direction from north to south. The greater axis may be considered a line of 30 myriameters § drawn from Laon to Blois. The outline of this polygon passes near the towns of Laon, La Fere, Noyon, Clermont, Beaumont, Gisors, Mantes, Houdan, Chartres, Chateaudun, Vendome, Blois, Orleans, Cosne, Montargis, Nemours, Nugent-sur-Seine, Sezarme, Epernay, and Rheims. Throughout all this extent the Paris strata

From the Annales des Mines, vol. i.

+ Dictionnaire de Geographie Physique; part of the Encyclopedie Methodique. 7,100 sq. miles, English. 328,091 English yards.

rest upon the chalk, which forms, as MM. Cuvier and Brongniart have observed, a vast belt around the Paris basin. (See Pl. LXXVII.)

a

That part of these limits north of the Seine is easily determined, being marked by its physical as well as its geological character. The Paris strata have, throughout, the form of chain of hills, more or less indented, which rise above the chalky plain. This latter, as it approaches the foot of these hills, becomes lower, and of a more even surface than usual.

MM. Cuvier and Brongniart have described a great number of these chutes of the Paris strata towards the plain of chalk; but as they have not mentioned that near Damerie and Rheims, I will here describe it.

The chalk, which to the east of Paris is concealed by the strata of a posterior formation, begins to appear in the valley of the Marne below Dormans, and rises, as we proceed up the valley, so that, on arriving at the plain of Champagne, we see it forming the bases of the hills to the height of some metres above the level of the plain. This fact, which occurs also in several other parts of the borders of the Paris beds, proves, that a part of the valley of the Marne has been hollowed in the chalk, and indicates also that the low plain which occurs round the hills of the Paris strata has not merely arisen from its being the accidental form of the chalk originally, but that, to a certain extent, it is owing to the same cause as that which has worn the outer edges of the hills into the great number of irregularities which are every where met with.

1 have not met with the plastic clay formation in this part, but from the observations of M. Desmarest, jun. it appears in the form of blackish earth, often of sand, sometimes of clay, and almost always impregnated with carbonaceous matter. These black strata, on which M. Desmarest proposes to publish, have much resemblance to those that are dug for the purposes of preparing sulphate of iron, and which are very common in the northern part of the Paris basin, and even in the chalky plain, where they constitute isolated deposits in the form of islands or small basins. The agreement of these black pyritous earths with the plastic clay will doubtless add much to the history of that formation of which it considerably increases the extent, at the same time that the occurrence of some of the fossils characteristic of the lime-stone with cerithia, in some of the beds of these black earths,* shows that there is a great connexion

* I have myself observed only two of the deposits of strata containing cerithia, One is at St. Marguerite, near Dieppe, where they form a small basin in the chalk. This consists of a series of beds of sand and clay, of which the first alternate with beds strongly impregnated with carbonaceous and pyritous matter, which are dug for making sulphate of iron, and beds of shells more or less broken, in which are distinguishable cerithia, and some bivalves, which I believe to belong to the genus cytherea. The other deposit is near Chateau-Thierry (Dep. of Aisne), where the valley of the Marne presents some blackish clay full of shells, among