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and therefore, supposing an interstice or valley between any two such monstrous precipices as these, the effect to an ere at the top must needs be most frightful and ghastly, and yet it may be justly questioned, could the trial be made, whether it would range any lower than the low-water mark of the great Æthiopic or Indian ocean. There is a perpendicular opening in the peak of Derbyshire, called Elden Hole, which Mr. Cotton plumbed to the depth of 884 yards, and the lead still drew; but he could never get the plummet so low afterwards*: but, take it at the greatest depth, they who are acquainted with the surface of the earth in those parts, will hardly think the bottom of this pit sinks beneath the edge of St. George's channel, on the coast of Lancashire. But these hideous chasms, as was observed, be they never so deep, afford no flames, no smoke, and therefore cannot be spiracles to an abyss of fire: and as there are no vents on the dry land, there can be none in those parts of the terraqueous globe which are covered with water; for the fluid would necessarily run in and extinguish the fire. Whereupon one cannot help remarking, that it is much more probable there should be an abyss of water at the centre, to which the scriptures give so much countenance, or a Terrella with Dr. Halley, than a globe of fire; for if any chinks were left at the formation of the earth originally, or have since happened by earthquakes, or any other means, the water, (and we know that the superficies of the earth is every where so far as we poor mortals have penetrated, replete with water) would of course rush in and lodge there.

But what, have the miners nothing to say? truly, very little to the present purpose. Heats and damps have been accounted for above, and the inines universally, throughout the whole face of the globe, are in mountains, it being a maxim among these gentry that they are never to be sought for in plain champaign countries. Admitting then a shaft should sink 200 fathom, it would not pass beneath the highwater mark; but the question ought to be put, how far the mine has gone below the medium of low and high water, and

supposing the excrescences on the surface of the earth were all pared off in order to make a smooth and even terraqueous sphere, no mines, I am persuaded, except perhaps some tin-mine near the shore in Cornwall, have even run deeper than that term. The plummet, I believe, has gone

* In the additions to Camden, col. 593, it is said to have been plumbed 800 fathoms, but that is a mistake.

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further towards the centre, than any thing in the world besides, and yet we are told that the sea is no where above a German mile deep, which is almost nothing in comparison with the semidiameter of the earth as specified above. But how are matters circumstanced in the great deeps ? not at. all favourably for the hypothesis of a central fire; there are no plants, nor any fish, those regions being too cold, as say, the philosophers, for the spawn of fish to quicken there.

But perhaps authority swayed most, and the modernsfounded their notion on the ancient Tartarus. This I fear is a misapprehension, for Hesiod places it under and not in the middle of the earth, * and accordingly our Milton has judiciously seated it far without this terraqueous globe.

These observations, Mr. Urban, are very superficial, and are only thrown out in order to induce some able hand to give this question, which certainly merits it, a thorough discussion, and it would give me great pleasure, as I dare say it would you, to see it undertaken by some adequate pen.

I am, Sir,
Your most obedient,


1753, Feb,

XII. History and Culture of Cochineal.

COCHINEAL is greatly esteemed throughout Europe for the richness and excellence of its die: it has hitherto been produced only in the Spanish West Indies, but our newspapers tell us, that an attempt is now making to produce it in Spain, and as the nature and origin of it are not very generally known, it is hoped the following particular and authentic account of it will not be unacceptable to the public,



It was not long ago believed that Cochineal was the seed of a plant; an opinion which probably took its rise from the circumstances of its being found upon, and gathered from the leaves of a West Indian shrub: but certain it is that Cochineal belongs to the animal, and not to the vegetable

* Hesiod. soyou 720, 721, et M. le Clerc ad. v. 728.

kingdom. The grains of Cochineal are each of them a little animal, which, when alive, greatly resembles a wood-louse, and from this resemblance it takes its name; for the Spaniards who first brought it into Europe ard gave it its name, call a wood-louse Cochinilla. These animals do not indeed roll themselves up, on being touched, as the wood-lice do, nor are the largest of them bigger than a sheep-tick.

The plant, or shrub, whereon these little animals are bred, nourished, and brought to perfection, is called, in the West Indies, Nopal, or Nopalera, and is a sort of fig-tree. It is indeed rather an heap of leaves than a shrub. After the trunk or stem has risen a little above the ground, it divides itself into several arms or branches, and the trunk itself and its several ramifications are full of knots: each of these knots sends out a leaf, and from the end of that leaf springs another, and so on till the plant arrives at its full growth. Those leaves which spring first and are nearest the trunk or branches, are the largest: the leaves are pretty long and not flat, but somewhat rounded, or convex, and full of little protuberances, and covered with a thin and delicate membrane which always preserves a lively green colour. Its flower is small, and like a flesh-coloured ball, in the centre of which appears the fig; and as the fig increases, the flower decays and loses its colour, till at last it falls and leaves the fig alone. When the fig is ripe, its outer skin, or husk, is white, but its pulp or substance is of a deep red: it is very wholesome and pleasant to the taste, but it tinges the urine of those that eat it, and makes it look like blood, a circumstance which has often given great uneasiness to those who were ignorant of this property of the fruit.

The nopal is propagated thụs: a number of holes are made in a line, about half a yard deep, and about two yards distant from each other: in every hole is put one or two leaves of the nopal well spread and stretched out, and then covered up with earth, and from each hole there springs á new plant. The grounds in which it is cultivated ought to be well weeded and kept clear of all other herbs whatever.; for "they deprive it of its due nourishment. The plants should be pruned soon after the Cochineal is gathered, and all superfluous leaves cut away: they will put out fresh leaves the following year, and by these means will become more strong and vigorous. But it is to be observed that the Cochi nillas which feed upon young plants, are larger and of a bétter quality than those which are gathered from plants which have stood some years.

The Cochinillas live upon the leaves of the nopal, and are

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fed and nourished by sucking their juice. The juice of the leaves is watry and colourless, but these animals in converting it into their own substance, change it to a fine crimson colour. One thing very remarkable is, that the Cochinillas do not gnaw nor devour the substance of the leaves, nor do the leaves suffer the least perceivable hurt or injury by their feeding upon them. It is probable that the little animals only suck the grossest juices through the pores of the thin membrane which covers the leaves.

When the Cochinillas are come to their full growth, they gather them into earthen pots, close stopped, that they may not creep out: and soon after they kill them in order to prepare them for sale. The Indians have three different ways of killing them, viz. By hot water, by the fire, or by exposing them to the heat of the sun. From these different methods there arises a great variety in the colour of Cochineal, some grains being of a brighter and much better colour than others. But whichsoever of the three methods is pursued, there is a proper degree of heat which must be carefully observed: when water is used, a sufficient quantity duly heated is sprinkled upon them: they who kill them by fire, put them into ovens properly heated: but the best Cochineal is that which is prepared by the heat of the sun.

In order to have the Cochineal in its utmost perfection, it is not only necessary to choose the best method of killing and preparing the Cochinillas, but also to know the right time for gathering them off the leaves of the nopal; but the knowledge of this is only to be attained by practice and ex perience, and no certain rule can be established for it: and it is observed that the Cochineal of the several provinces of the West Indies is better or worse, just as the Indians employed about it are more or less skilful and experienced.

The Cochinillas in' several particulars may be compared to the silkworms, and especially in the manner of laying their eggs. Such of them as are destined to breed, are taken from the leaves of the nopal when they are in full vigour, and put into baskets well closed and lined with linen, close wrought and folded several times, that none may be lost; there they lay their eggs and soon after die. The baskets must be kept close covered up till the proper season of the year arrives for laying the Cochinillas upon the leaves of the nopalera. The time proper for laying them upon the leaves is in the month of May or Junė, when the nopalera is in its prime: and when about this time the baskets are opened, the Cochinillas appear about the size of small mites, and by observing them attentiyely you may just perceive them move. In this state they scatter them upon the leaves of the plants: an hen's egg shell fall of them is sufficient to furnish a whole pl:nt.

There are several things either very pernicious, or fatal to the Cochinillas. If strong northerly winds come on soon after they are laid upon the leaves, they are all destroyed. Rains, snow, mists, and frosts, often kill them, and at the same time blast the leaves of the nopalera. The only remedy in these cases is to warm and smoke them. Hens and some small birds eat the Cochinillas, and so do several sorts of worms and insects, which breed in the places where the nopaleras grow. Great care therefore is taken to keep off the birds, and to destroy the reptiles and insects which are prejudicial to them.

The Cochinillas are bred in the provinces of Ooxaca, Flascala, Chulula, New Galicia, and Chiapa, in the kingdom of New Spain, and also in the provinces of Hambato, Loja, and Tucuman in Peru. But although the Cochinillas and nopalcras abound in all these provinces, yet they are not properly managed and prepared for sale in any but that of Ooxaca, and there only do the Indians make it their business to cultivate and take care of them: in all the others the nopaleras are wild and uncultivated, and the Cochinillas breed of themselves without being looked after, and therefore the Cochineal gathered in these provinces is much inferior in goodness to that of Ooxaca: not that the nopaleras or Cochinillas are of a worse kind, but because they are not properly managed and cultivated.

In the kingdom of Andalusia in Old Spain, there is a plant called Tuna, which very much resembles the nopal, and bears a fruit like it. It only differs from the nopal in respect of its leaves, which are broad and flat and full of prickles of different sizes. It is therefore thought that the tuna will be as proper food for the Cochinillas as the nopal: and as the climate of Andalusia is dry and temperate, and agreeable to the Cochinillas, the attempt to breed them there will probably meet with success.

1753, Feb.

XIII. Experiments on Animal Digestion.

MODERN naturalists and physicians rest the business of digestion on these two queries: 1. Is it the work of tritura

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