The Plague at Marseilles Consider'd by Richard Bradley (online e book reader TXT) 📕

Cattle and Plants, are not universal? And why the Plague should not be as well in India, China, the South Parts of Africa and America, as in these Parts of the World? (For I do not find it has ever been in those Places.) This Query gives me a farther Opportunity to suggest, that Insects are the Cause of it, and that they are brought with the Easterly Winds. In the first place, so far as I can learn, there is not naturally in America any one Kind of Creature or Insect that is found in any other Part of the World, and the Plants likewise are all different from those of other Countries; as it is the same in India, China, &c. whose Products are quite different from what we find elsewhere. Supposing then that these pestiferous Insects are only the Produce of Tartary, let us consider to what Parts of the World they may be carry’d from thence with the Easterly Winds; and whether India, China, the South of Africa and America, are not beyond their Reach, or can reasonably be affected by them.

Whoever considers the Disposition of the Land and Water in the Globe, may thus account for the Passage of these Insects, with an Easterly Wind from Tartary, to all the Parts of Europe, Asia-Minor, Palestine, Barbary, and other South Coasts of the Mediterranean Sea, whither, ’tis highly probable, they may come, without meeting any thing in their Way to obstruct their Course.

The best Maps do not lay down any Mountains of Note between Tartary and the places which have been subject to the Plague: The Alps run parallel with the Winds coming from Tartary, and therefore does not any Way hinder their Passage: The Mountains of Dalmatia are not high enough to prevent the Passage; or if they were, the Caspian Sea is sufficiently large to let them pass to the South Parts of Europe, the Mediterranean Sea, and the North Coasts of Africa, even to their most Western Bounds.

Now it may be expected, perhaps, by some, that these Winds should yet continue their Progress as far as America; but as yet, so far as I can learn, these Land-Winds, when they have blown with the greatest Force, and have been of the longest Continuance, have not reach’d farther than about three hundred Leagues beyond the Western Coasts of Europe, which is a Trifle in Comparison of the vast Ocean between us and America: Besides, it is my Opinion, that the Winds which blow over so vast a Tract of Land, as these Tartarian Winds must do, that I suppose convey and support the pestiferous Insects, are of so different a Nature from the Winds coming from the Ocean, that ’tis likely those Creatures which would subsist in the one, would be destroy’d by the other: So that if I am right in this Conjecture, America cannot be subject to the Plague.

Mount-Atlas, which is a vast Ridge of Mountains, running from the Ocean almost as far as Egypt, and are back’d with the Desarts of Lybia, may very likely obstruct the Passage of these Insects to the South of Africa; and for that Reason, perhaps, secure that part of the World from Plagues. So likewise Mount-Caucasus, or Ararat, which is one of the highest Ridge of Mountains in the World, running from East to West, thro’ Persia and India, may secure the South Parts of those Countries from the Plague, by stopping the Passage of those infectious Creatures, if any Winds from Tartary should happen to blow them that Way: And as China lies to the East of Tartary, so it must be Westerly Winds which must infect that Country with the Plague, if it proceeds from what I imagine: But we do not yet find that Westerly Winds are frequent in those Parts; or if they are, we may be assur’d they cannot blow at the same time when the Insects are hatch’d and carried the contrary Way by the Wind from Tartary. We are inform’d, that upon the Coast of China, the Winds are so regular, that from October to March they continually blow from the North-East, and from that Month to October, the direct contrary Way.

And Plants are no less subject to be destroy’d by Insects, than Men and Quadrupedes, is I have explain’d in the Chapter of Blights, in my New Improvements of Planting and Gardening.

Plants of all degrees are subject to Blights, which are so variously communicated to them, that sometimes a whole Tree will perish by that Distemper; now and then a few Leaves, or Blossoms only, and perhaps a Branch or two, will be shrivel’d, or scorch’d by it, and the rest remain green and flourishing. I have yet never observ’d this Disease to happen among Plants, but upon the blowing of sharp and clear Easterly Winds, which are most frequent in England about March; but sometimes happen in other Months. It is very observable, that the Caterpillars generally attend these Winds, chiefly infecting some one sort of Tree more than another, and even then not every where upon the kind of Tree they attack, but some particular Branches only; from which Observations I think we may draw the following Inferences, either that the Eggs of those Insects are brought to us by the Easterly Winds, or that the Temperature of the Air, when the Easterly Winds blow, is necessary to hatch those Creatures, supposing their Eggs were already laid upon those infected Parts of the Trees the preceding Year.

The Blights which are attended with large Worms or Caterpillars, seem to be rather hatch’d with the East Wind, than that the Eggs of those Creatures are brought along with it; but those Blights which produce only those small Insects which occasion the curling of the Leaves of Trees, may proceed from Swarms of them, either hatch’d or in the Egg, which are brought with the Wind.

Some perhaps may object, that the East Wind is too cold to hatch these Creatures; how comes it then that we find them hatch’d when those Winds reign? Or is it reasonable to conjecture that the same degree of Heat is necessary to enliven an Insect as is required to hatch the Egg of a Pullet? The Insects of Norway, Iceland, and such like cold Climes, must certainly have less Heat to produce them, than Creatures of the same Race must necessarily have in those Climates which lye nearer to the Sun. Every Creature, without doubt, requires a different Period of Heat or Cold to enliven it, and put it in Motion, which is prov’d by so many known Instances, that I conceive there is no room for any dispute upon that score.

But there may yet be another Question, viz. Whether it is not the East Wind of it self that blights, without the help of Insects? But that may be easily resolved on my side; for that if it was the Wind alone that blighted, then every Plant in its way must unavoidably be infected with its Poison; whereas we find the contrary on a single Branch it may be, or some other distinct Part of Plants.

And again, to shew how reasonably we may conjecture that ’tis Insects which thus infect the Trees, let us only consider, that every Insect has its proper Plant, or Tribe of Plants, which it naturally requires for its Nourishment, and will feed upon no other kind whatsoever: Therefore ’tis no wonder to see one particular sort of Tree blighted, when all others escape; as for Example, that Wind which brings or hatches the Caterpillars upon the Apple-Trees, will not any way infect the Pear, Plumb, or Cherry with Blights, because, were the Shoals of Insects natural to the Apple, to light only upon those other Trees mentioned, they would then want their proper Matrix to hatch in; or if they were hatch’d already, they would Perish for want of their natural Food; so that ’tis morally impossible that all sorts of Trees should be blighted at the same time, unless the Eggs of every kind of Insect, natural to each Tree, could be brought at one time with the Wind, or that an Easterly Wind could contain in it at once, as many differing Periods of Cold or Heat, as would be requir’d to hatch and maintain each differing kind of those Creatures.

The common People in the Country seem to be of my Opinion, that Blights are brought by the East Winds, which they are so well satisfied brings or hatches the Caterpillar, that to prevent the too great Progress of Blights, it is common for them when the East Winds blow, to provide large Heaps of Weeds, Chaff, and other combustible Matter on the Windside of their Orchards, and set them on Fire, that the Smoak may poison either the Insects or their Eggs, as they are pass’d along. By this Contrivance I have often known large Orchards preserv’d, when the neighbouring Parts have suffer’d to the Loss of all their Fruit.

And I have also seen these Fires made with good Success to destroy the Caterpillars, even after they were hatch’d, and had began to devour the Trees, by suffocating them, and forcing them to drop to the Ground, where they have been swept up in large Quantities, and kill’d. I have heard it affirm’d by a Gentleman of Reputation, that Pepper-Dust, being powder’d upon the Blossoms of any Tree, will preserve them from Blights, which may be, because Pepper is said to be present Death to every Creature but to Mankind. Now altho’ this last Secret is too costly for common Use, yet it may be of Service in some particular Place for the Tryal of a new Tree, where a Taste of the Fruit is desired, and besides it helps to inform us, that Blights are occasion’d by Insects, or their Eggs, lodging upon a Plant, and that Pepper Dust will not suffer them either to live, or to be hatch’d.

Another Remark (which to me is Demonstration) that Blights proceed from Insects, or their Eggs (being brought with the Easterly Winds) was the total Destruction of the Turneps, Ann. 1716, on the West Side of London; about October we had dry Easterly Winds for a Week or ten Days, and several thousand Acres of Turneps, which were then well grown, turn’d Yellow and decay’d, unless in such Places only as were shelter’d by Hedges, Houses, or Trees, where they remain’d Green ’till the Insects, which came with the Wind, in about a Week’s Time, destroy’d those also. Some Farmers imagin’d that the Birds which were there in great Flocks, had eaten the Leaves of their Turneps, and contriv’d all Means possible to destroy them, ’till I convinc’d them that the Birds were rather Friends than Enemies and came there to feed upon the Caterpillars, which were in such great Numbers, that each Turnep-plant had not less than a Thousand upon it; and that Insects frequently pass in Clouds and numberless Armies after this manner, is plain from several Instances, which have happen’d in my Time, and one of them (I think in June, Ann. 1717) passing over London were suffocated (I suppose) with the Smoak of the Sea-Coal, and drop’d down in the Streets, insomuch that a square Court belonging to the Royal Society was almost cover’d with them; these were of the Fly Kind, and fully perfected.

It may be asked, perhaps, how these Insects came to destroy the Turneps only, and not touch the other Greens of the Fields, as Cabbages, Carrots, Parsnips, and the like? Every Herb has its peculiar Insect, like the Trees I have mention’d: Nay more than this, the Insects which Nature hath design’d to prey upon the Flower of a Plant, will not eat the