From the "Pennsylvania Chronicle" for 1768. LETTERS FROM JAMES LOGAN.

darted with such a rapidity, can from any assignable cause, deviate in fact from a right line in the manner it bly be found a plenary solution.

of the crooked appearance of lightning.

Part of a letter from the late James Logan, of Philadel phia, to the late Sir Hans Sloane. From an original MS. communicated by Peter Collinson, Esq.

"It may perhaps be needless to add any thing in con

firmation of Dr. Wallis' solution of the sun and moon appearing so much larger at rising and setting, than in a greater altitude; though some have gone on very absurdly, and still go on to account for it from vapours; which I remember was given me in my youth for the

true cause of it.

"It is true, indeed, that it is these vapours in the atmosphere alone, that makes these bodies, when very near to the horizon, appear in a spheriodical form, by retracting, and thereby raising (to sight) the lower limb more than the upper, yet these can be no cause of the other. Sun or moon, each subtending about half a degree, appear in the meridian of the breadth of eight or ten inches, to some eyes more and to others less, and in the horizon to be two or three feet, more or less, according to the extent of ground they are seen over. "But if one has an opportunity, as I have here frequently had, of seeing the sun rise or set over a small eminence at the distance of a mile or two, with tall trees standing on it pretty close, as is usual in woods without underwood, his body will then appear to be ten or twelve feet in breadth, according to the distance and circumstances of the trees he is seen through; and where there has been some thin underwood, or a few sapplings, I have observed that the sun setting red has appeared through them like a large extensive flame, as if some house was on fire beyond them.

"Now the reason of this is obvious, viz. that being well acquainted with trees, the ideas of the space they take up are, in a manner, fixed, and as one of those trees subtends an angle at the eye perhaps not exceed ing two or three seconds, and would scarce be distinguishable were it not for the strong light behind them, the sun's diameter of about thirty inches takes in several of them, and therefore will naturally be judged vastly larger. Hence it is evident, that those bodies appear greater or less, according to the objects interposed, or taken in by the eye on viewing them, and to this only is the phænomenon to be imputed.

J. LOGAN."

"I observed the ingenious gentleman Stephen Hales, in his Vegetable Staticks, to mention that phænomenon of the streaks or darts in lightning, in thunder-storms appearing crooked and angular, (I do not remember his words) as a thing unaccounted for, and therefore guessed at a solution of it; but, if I mistake not, I some time since discovered the true one, which was thus having a sash window glazed with bad, or waved glass, and sitting about twelve feet distance from it, one of my people was carrying by that window, at some distance from it, a long lath on his shoulder, which, through that glass, appeared to my view exactly in the form that those streaks of lightening are seen, and as thunder is generally pictured in the hand of Jupiter. And any one with such wavy glass may very easily make the like experiment.

"Now it is evident, that the clouds are generally distinct collections of vapours like fleeces, and therefore, that the rays of light through them must pass through very different densities, and accordingly suffer very great refractions, as great at least as could be caused by one thin plate of glass, which, notwithstanding, will very fully produce the same phænomenon. From thence, therefore, undoubtedly that appearance must arise; for it is most highly absurd to imagine, that fire,

J. LOGAN."

PENNSYLVANIA SILK WORMS.

Observations on the native silk worm of North America, by Moses Bartram, member of the American Society, held at Philadelphia, for promoting useful knowledge.

READ BEFORE THE SOCIETY, MARCH 11, 1768. I had for a long time, a desire to know, if some of the wild silk worms of North America could, with proper care, be propagated to advantage; accordingly, in March 1766, I made an excursion along the banks of Schuylkill, in search of some pods or cocoons, in which the worms spin themselves up and lie concealed all the winter, in the nymph state, preparing for a change in the spring, namely, from an aurelia to a fly.

I was so lucky as to find five cocoons that had live sound nymphæ in them. These five I placed in my garret opposite to a window, that fronted the sun rising. I did this that the warmth of the sun might forward their coming out.

May 10. One of the flies came out; but the window happening to be left open it made its escape.

May 13. One of my pods produced a large brown fly, beautifully spotted, next day two more of them produced, each a fly.

May 18. One of the flies, which came out of a large loose pod, began to lay eggs. On the 22d, the other two, which were males, grew very weak and feeble and unable to fly. Next day one of them died, and the day following the other died; the female fly all this time continuing to lay eggs; on the 24th at night she also died, having laid near three hundred eggs. May 31, My last pod produced a large female fly, of the brown kind like the rest. But there being no male I could expect no increase from it. June 3d, She began to lay eggs and continued some days. On the 8th she died, having laid upwards of two hundred eggs. These which my last fly laid looked at first large and full, but in a few days they began to shrivel and be indented in the middle, as did all the rest, however, I folded them all up in separate papers and laid them by, to see if any would hatch the spring following

The male fly is less than the female, but his colours are brighter and more beautiful.

In the spring of the year 1767, I examined the eggs, and found them all dry, and not like to produce worms; from whence I concluded they had not been impregnated by the males. This was a disappointment to me.But being still of opinion, that they might be propagated, I determined to make another trial with more caution and circumspection. Accordingly I set out in search of cocoons, and gathered several of them both from the swamps and upland. Those from the swamps I got chiefly off the alder; those from the upland, off the wild crab-tree; and the viburnum or black haw bushes.

These pods I placed as I had the others, before my garret window, where the sun might shine on them, as soon as it arose, and a great part of the forenoon.When I expected the flies were near coming out, I tacked coarse cloths up against the windows on the inside, not only to darken the room, but also for the flies to settle on, and to prevent them, in attempting to make their escape, from beating their legs and wings to pieces against the glass, which I found to be the case last year, and which it is probable, prevented their copulating.

May 16. Three of my cocoons produced each a fine large fly of the brown kind, the same as those of last year. The two following days two more flies made their appearance, and one of the eldest began to lay eggs, which not being impregnated, dried up and yielded no increase.

1831.]

May 19. One of the males that came out on the 16th copulated with the female that was produced on the 18th. They continued together about twenty-four hours; a common case with most of the insect tribe, And somewhich lay a great number of eggs at once. thing similar may be observed in some other animals. May 22d. This female began to lay eggs which looked plump and fine. Though I had now several flies, yet this was the only one from which I had any in

crease.

June 2. The last of my flies died, all expiring regu. larly as they came out. The period of their existence is short, seldom exceeding nine or ten days, though some of the females lived to the age of fourteen or fifteen, as I found by one I had last year.

41

June 4th, 5th and 6th. The eggs continued hatching and producing young worms.

June 9. Those first hatched left off feeding, shrunk up short and seemed motionless. I imagined they were sick and changed their food, trying almost every kind of vegetable, in hopes of finding something that would agree with them better; but all to no purpose. Having killed several in shifting them from one kind of food to another, while the rest continued in the same torpid state, notwithstanding all I could do, I thought all my hopes of raising them were frustrated and concluded they would perish,

June 9. I was agreeably surprized to see the little animals, that I had given over as dead, creeping out of their old skins, and appearing much larger and more beautiful than before. Finding themselves disengaged, in a little time, they turned about and fell to devouring their old coat, which seemed a delicious repast to them; after which they rested about twelve hours, and then began to feed on leaves as formerly with great

eagerness.

defence.

6

August 10. The last worm left off feeding, and like the rest wrapped itself up, in which state I expect they will all remain, until May next, when each of them, I hope, will produce a beautiful fly.

It seems strange there should be an interval of no less than nineteen days between the time the first and last worm began to spin, though they were all hatched within three or four days of each other, which was nearly the space of time the parent fly was laying the egg.-Whether this was owing to the weakness or strength of the vital principle in some, more than in others, or whether to the shifting their food, or to their being frightened, and thereby prevented from feeding, I cannot tell. Farther experiments may possibly explain the matter.

The method I took to raise these worms, with the least trouble to myself, as I live in town, and consequently had to bring food out of the country, was as follows: I filled several bottles with water; in these bottles I placed branches of such vegetables as the worms fed on. I placed the bottles so near each other, that when any of their food withered, the worms might crawl to what was fresh. By this means I kept their food fresh for near a week. I always kept the bottles full of water, whereby the worms were supplied with Without it drink, which seems necessary for them. they will not feed kindly. They commonly crawled down two or three times a day, drank heartily, and then returned to feeding. The leaves of the apple tree seemed as agreeable to the worms as any I tried; and they answered best as they kept fresh in the water longer than any other.

From sundry experiments, I found the worms averse On whatever they first begin to changing their food. to feed, they keep to it. If any should incline to propagate these worms, I would propose the following method. Let long narrow troughs be made, with a number of notches along the edges. In the bottom of the troughs, on the inside, let pieces of straight wood be fixed, so that the branches, on which the worms are to feed, may lie in the notches, and their ends be fixed under the piece of wood at the bottom. This would keep them steady, and lying thus inclined, they would more freely imbibe the water for the refreshment of the leaves. The dung of the worms would fall clear of the troughs, and the water thereby be clean for drink. The troughs should be always kept full of water, and placed in a shade, secure from the violence of the wind, which might shake down the worms; but not too much confined, because a little air is agreeable to them. Through a hole in the bottom of the trough, the water might be let out every two or three days, and the troughs filled again with fresh wa ter, which by this means would continue sweet and clean.

By this method, I am persuaded, they might be raised to advantage, and perhaps, in time become no con

temptible branch of commerce. They appear to me much easier raised than the Italian or foreign silk worms. I did not lose one by sickness. They hatch so late in the spring that they are not subject to be hurt by the frost. Neither lightnings nor thunder disturb them, as they are said to do foreign worms. And as they lie so long in their chrysalis state, the cocoons may be unwinded at leisure hours in the ensuing winter.One thing more in their favour is, that one of their cocoons will weigh more than four of the foreign worms; and, of consequence, it may be presumed, will yield a proportionable greater quantity of silk. These properties, not to mention their being natives, and therefore accustomed to our climate, and the vegetables, on which they feed, must render them much more promising than the eastern or foreign worms, and it is to be hoped, will induce some who have leisure to make further trials of them. Any time before the middle of May will do to collect them. Now is the time to collect the cocoons, and with a little pains a sufficient number of them may be found in almost any swamp or level piece of land, to make a begining.

I would advise them to prepare boxes, in the following manner. They may be of any convenient length, about six inches deep, and four or five wide; without a bottom, and instead of a close cover for the top, let there be strips of wood nailed on, so close to each other as not to admit the worms through-let there also, be several holes in one or both sides, big enough for the worms to be put in at, as they want to spin, and then stopped up the inside should be washed with a solution of gum arabic, or cherry tree gum-the box may stand on any flat place to prevent the worms getting out; and when the silk is to be unwound, by immersing the boxes in warm water, the cocoons may be taken out without breaking the threads of silk.

[Extracted from the minutes, and published by order of the Society, in order to encourage further experiments, and to assist any who shall be inclined to make them.]

CHARLES THOMSON, Secretary.

LANCASTER COUNTY STATISTICS.

The following statement has been compiled from the Assessor's returns in the Commissioner's office. As many of them may be defective, we will be obliged to any person who may supply us with a correct list, that we may be enabled to lay it before our readers.

Lancaster city contains seventeen distilleries, one snuff mill, four tanyards, five breweries, and two potteries.

Lancaster township, four distilleries, one fulling mill, four grist-mills, and one factory.

Conestoga, one forge, nine distilleries, one tanyard, eight grist-mills, and three saw-mills.

Lampeter, eleven distilleries, three tanyards, and twelve grist-mills.

Sadsbury, three forges, one distillery, three tanyards, two fulling-mills, five grist-mills, and two saw-mills. Salisbury, one forge, thirteen distilleries, one tanyard, one fulling-mill, nine grist-mills, and ten saw-mills. Columbia, two tanyards, one grist-mill, and one brew

ery.

Caernarvon, three forges, four distilleries, three tanyards, three grist-mills, one saw-mill, and two hemp

mills.

Leacock, seven distilleries, one fulling-mill, and five grist-mills.

Strasburg, nine distilleries, one tanyard, one fulling mill, twelve grist-mills, twelve saw mills, one oil-mill, and one pottery.

Little Britain, two forges, five tanyards, two fulling mills, six grist-mills, seven saw-mills, three clover-mills, and one factory.

East Donegal, thirteen distilleries, two tanyards, four grist-mills, one saw mill, and two breweries.

West Donegal, eight distilleries, one fulling-mill, and four grist-mills.

Rapho, four furnaces, nineteen distilleries, three tanyards, three fulling-mills, eleven grist-mills, six saw-mills and one hemp-mill.

Manheim, nine distilleries, one tanyard, four gristmills, three saw-mills, one hemp-mill, and one oil-mill. Elizabeth, one furnace, one forge, three distilleries, one tanyard, two fulling-mills, ten grist-mills, seven saw-mills, one hem-pmill,and one oil-mill. Cocalico, two carding machines.

East Hempfield, fourteen distilleries, one tanyard, three grist-mills, one saw-mill, one hemp.mill, and one oil-mill.

Coleraine, two forges, two grist-mills, and nine sawmills.

Warwick, fourteen distilleries, three tanyards, one fulling-mill, thirteen grist-mills, seven saw-mills, one brewery, two hemp-mills, one oil-mill, one carding-machine, and one snuff-mill.

Dromore, one furnace, one distillery, one tanyard, one fulling-mill, three grist-mills, five saw-mills, two oil-mills, one carding machine, two tilt hammers, and one rolling mill.

Martick, one furnace, one forge, two distilleries, four tanyards, one fulling-mill, six grist-mills, and six sawmills.

Mountjoy, seven distilleries, one tan-yard, six gristmills, and one saw-mill.

Manor, thirty distilleries, fifteen grist-mills, four sawmills, and one factory.

Earl, eight distilleries, one fulling-mill, and four gristmills.

As far as our means of calculation extend, Lancaster county contains seven furnaces, fourteen forges, one hundred and eighty-three distilleries, forty-five tanyards, twenty-two fulling-mills, one hundred and sixty-four grist-mills, eighty-seven saw-mills, nine breweries, eight hemp-mills, five oil-mills, five clover-mills, three factories, three potteries, six carding machines, three papermills, two snuff-mills,seven tilt-hammers, and six rollingmills.

The Assessor's returns from Bart, Brecknock, Cocalico, and West Hempfield being defective, no information could be derived from them-we therefore will be obliged to any person, who will furnish us with a list of distilleries, tanyards, &c. of any of the above townships. Lancaster Miscellany.

For the Register of Pennsylvania.

THE ALCHEMIST.

No. XXI.

"These degenerate days"-Pope's Homer.

It seems to be a generally received opinion that ancient times were better than our own. A reverence for antiquity is taught us in our earliest schools, it is strengthened at our colleges, and confirmed by the historian, the moralist, and the divine, in our riper years. It is not left to our own judgments or feelings, but is dictated so early and so constantly, that we can scarcely remember a time when it was not spoken of as a point of duty. It is worked into our very constitutions, and the question whether has mankind degenerated, is at first, almost as startling to settled prejudices, as the question whether is the christian religion authentic, would be to a well regulated conscience. tion, our classics and our prejudices are all alarmed, and our feelings answer the question, without consulting our understandings. Homer asserted that the world had degenerated, and whether succeeding times have adopted his opinion as authority, or have thought their

Our educa