lar as this may appear, it is not more fo than the doublet refraction produced by the Ice-Land cryftal.-The next morning Prefque-Ifle was again invifible, and remained fo during our ftay at that pofition. Prefque-Ifle was about twenty-five miles diftant, its fituation very low.

The fame evening the wind began to blow brifkly from about two points weft of North, and continued to increase till the evening of the 14th, when it was more violent than any thing of the kind I had ever been witness to before, and continued till the evening of the 16th without the leaft intermiffion-Our tents were all blown down, and we were under the neceffity of fortifying our camp, by driving pofts near to each other, firmly into the ground on the windward fide, and filling up the vacuities with bushes in form of an hedge.---During the continuance of this wind, we frequently observed fmall black clouds hanging over the lake;---they had but little velocity, and were fometimes exhaufted, and disappeared without reaching

the shore.

From the large bodies of timber blown down about the lakes, it appears that hurricanes are not uncommon;Coxe obferves in his travels through Ruffia, that the lakes in that country are fubject to terrible storms.

No. IX.

An account of the Sugar Maple-tree of the United States, and of the methods of obtaining Sugar from it, together with obfervations upon the advantages both public and private of this Sugar. In a letter to THOMAS JEFFERSON, Efq. Secretary of the United States, and one of the Vice Prefidents of the American Philofophical Society by BENJAMIN RUSH, M. D. Professor of the Inftitutes and of Clinical Medicine in the University of Pennsylvania.

Read Aug. *19,1791

DEAR SIR,

IN

N obedience to your requeft, I have fet down to communicate to our Society through the medium of a letter to you, a fhort account of the Sugar Maple-tree of the United States, together with fuch facts and remarks as I have been able to collect, upon the methods. of obtaining Sugar from it, and upon the advantages both public and private, of this Sugar.

The Acer Sacharinum of Linnæus or the Sugar Mapletree grows in great quantities in the western countries of

all the middle ftates of the American Union. Those which grow in New-York, and Pennsylvania yield the Sugar in a greater quantity than those which grow on the waters of the Ohio. These trees are generally found mixed with the Beach, (a) Hemlock, (b) white and water afh, (c) the Cucumber tree, (d) Linden, (e) Aspen (f) Butter nut, (g) and wild cherry trees. (h) They fometimes appear in groves covering five or fix acres in a body, but they are more commonly interfperfed with fome or all of the foreft trees which have been mentioned. From 30 to 50 trees are generally

(a) Fagus Ferruginea. (b) Pinus abies: (c) Fraxinus Americana. (d) Magnolia acuminata. (e) Tilia Americana. (f) Populus tremula. (g) Jugians alba (oblonga.) (h) Prunus Virginiana, of Linnæus.

generally found upon an acre of ground. They grow chiefly in the richest foils, and frequently in ftony ground. Springs of the pureft water abound in their neighbourhood. They are when fully grown as tall as the white and black oaks, and from two to three feet in diameter, They put forth a beautiful white bloffom in the fpring before they show a fingle leaf. The colour of the bloffom diftinguishes them from the acer rubrum, or the common maple which affords a bloffom of a red colour. The wood of the Sugar Mapletree is of an inflammable nature, and is preferred upon that account by hunters and surveyors for fire wood. Its fmall branches are fo much impregnated with fugar as to afford fupport to the cattle--horfes, and fheep of the first fettlers during the winter, before they are able to cultivate forage for that purpose. Its afhes afford a great quantity of pot afh exceeded by few or perhaps by none of the trees that grow in the woods of the United States.

The tree is fuppofed to arrive at its full growth in the woods in twenty years.

It is not injured by tapping; on the contrary, the oftener it is tapped, the more fyrup is obtained from it. In this refpect it follows the law of animal fecretion. A fingle tree has not only furvived, but flourished after forty-two tappings in the fame number of years. The effects of a yearly discharge of fap from the tree in improving and increafing the fap is demonftrated from the fuperior excellence of those trees which have been perforated in an hundred places, by a small wood-pecker which feeds upon the fap. The trees after having been wounded in this way diftil the remains of their juice on the ground, and afterward acquire a black colour. The fap of these trees is much fweeter to the taste than that which is obtained from trees VOL. III. I which

Baron LaHontan, in his voyage to North America gives the following account of the Maple tree in Canada. After defcribing the black Cherry tree fome of which he fays are as tall as the loftiest oaks and as big as a hogfhead, he adds "The Maple tree is much of the same height and bulk. It bears no resemblance to that fort we have in Europe,”

L

which have not been previously wounded, and it affords more fugar.

From twenty three gallons and one quart of fap procured in twenty hours from only two of thefe dark coloured trees, Arthur Noble, Efq. of the state of New-York obtained four pounds and thirteen ounces of good grained fugar.

A tree of an ordinary fize yields in a good feafon from twenty to thirty gallons of fap, from which are made from five to fix pounds of fugar. To this, there are fometimes remarkable exceptions. Samuel Low, Efq. a Juftice of Peace in Montgomery County, in the ftate of NewYork informed Arthur Noble, Efq. that he had made twenty pounds, and one ounce of fugar between the 14th and 23d of April in the year 1789. from a fingle tree that had been tapped for feveral fucceffive years before..

From the influence which culture has upon foreft and other trees, it has been fuppofed, that by tranfplanting the Sugar Maple tree into a garden, or by deftroying fuch other trees as shelter it from the rays of the fun, the quantity of the fap might be increafed and its quality much improved. I have heard of one fact which favours this opinion. A farmer in Northampton County in the state of Pennsylvania, planted a number of these trees above twenty years ago in his meadow, from three gallons of the fap of which he obtains every year a pound of fugar. It was obferved formerly that it required five or fix gallons of the fap of the trees which grow in the woods to produce the fame quantity of fugar.

The fap diftils from the wood of the tree. Trees which have been cut down in the winter for the fupport of the domeftic animals of the new fettlers, yield a confiderable quantity of fap as foon as their trunks and limbs feel the rays of the fun in the spring of the year.

It is in confequence of the fap of these trees being equally diffufed through every part of them, that they live three years after they are girdled, that is, after a circular incifion is made through the bark into the subftance of the tree for the purpofe of deftroying it.

It is remarkable that grafs thrives better under this treet in a meadow, than in fituations expofed to the conftant action of the fun.

The season for tapping the trees is in February, March and April according to the weather which occurs in these months.

Warm days and frosty nights are moft favorable to a plentiful difcharge of fap. *The quantity obtained in a day from a tree, is from five gallons to a pint, according to the greater or lefs heat of the air. Mr. Low, informed Arthur Noble, Efq. that he obtained near three and twenty gallons of fap in one day (April 14, 1789,) from the fingle tree which was before mentioned. Such inftances of a profusion of sap in single trees are however not very

common.

There is always a fufpenfion of the discharge of fap in the night if a froft fucceed a warm day. The perforation in the tree is made with an ax or an auger. The latter is preferred from experience of its advantages. The auger is introduced about of an inch, and in an afcending direction (that the fap may not be frozen in a flow current in the mornings or evenings) and is afterwards deepened gradually to the extent of two inches. A fpout is introduced about half an inch into the hole, made by this auger and projects from three to twelve inches from the tree. I 2 The

The influence of the weather in increafing and leffening the discharge of the fap from trees is very remarkable.

Dr. Tonge fuppofed long ago (Philofophical Tranfactions No. 68) that changes in the weather of every kind might be better afcertained by the discharge of fap from trees than by weather glaffes. I have seen a journal of the effects of heat, cold, moisture, drought and thunder upon the difcharges from the fugar trees, which difpofes me to admit Dr. Tonge's opi

sion.