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pages of the months, the emersions of Ju- Page 78. July, 22d, at noon, the piter's first and second satellites, at the moon's declination is put down 3° 52' S. head of the columns, containing their It ought to be 2° 52' $. eclipses, are stated to be immersions. Page 88. The geocentric longitude of That these are errors is manifest from an Mercury on the 31st day of August is observation on page 153 of the same Al- stated to be 4 S. 4° 20. It should be manack. “Before the oppositions, (of 6 S. 4' 20'. Jupiter,) the immersions only of the first Page 90. The moon's declination on satellite are visible; and after the oppo- the 24th day of August is stated to bo sition, the emersions only. The same is 24° 5'. It should be 24° 55'. generally the case with respect to the These errors are offered to astronosecond satellite.” Now Jupiter passed mers and navigators, without comment. his opposition, in 1814, on the 23d astro. I would only observe, that Mr. Blunt nomical day of February, and did not "pledges his reputation it (the Nautical reach his conjunction with the sun till the Almanack) shall not in one instance de15th of September. In the intermediate viate from the English Edition;" and oftime, therefore, the immersions of his first fers a reward of “ ten dollars” for the disand second satellites were not visible. covery of an error. He has been written For 1816.

to several times on the subject; but his In Blunt's Edition.

answers were evasive and unsatisfactory. On the second page preceding the

EDWARD HITCHCOCK. first page of January, five Chronological Deerfield, (Mass.) Oct. 29, 1817. Cycles, twelve Ember Days, and twelve Moveable Feasts are wrong; answering To The Editors or THE AMERICAS to 1812, instead of 1816.

MONTALY MAGAZINE.
In the London Edition.

I notice a small error in Dr. Akerly's Page 66. June 19th, at noon, the valuable communication on the Locust moon's declination is put down, 0° 16' N. tree. He says it “is a native of the It should be 2° 16' N.

United States, but was not “known north Page 136. In the left hand column, at or east of the Potomac before the white the bottom, 21 is put where there should settlers brought it from thence." be 31; and there is nothing where there About 30 miles southeast from Catashould be 21. The geocentric latitude of wissy in Pennsylvania, on the road to the Georgian is also omitted on the 21st Philadelphia, there is a ridge called " the day.

Locust Mountain," on which this tree apFor 1817.

pears to be indigenous. The south part In Blunt's Edition.

of that elevated tract is encumbered by Page 109. On the 230 day of Octo- the Pudding Stone, which is very loosely ber, the sun is said to enter ny, Virgo; cemented, and to its disintegration ought which is impossible. It should be in; to be referred the origin of the soil. But Scorpio.

nearly all the declivity on the northwest In the London Edition.

side

presents new scenery. A reddish Page 48. April 15th, at midnight, the loam, moderately fertile, rests on rocks moon's parallax is put down fifty seconds of Mica-slate, if my recollection is distoo small.

tinct, and from the scrubby oak and pine For 1818.

of the opposite side, we pass into a forest In the London Edition.

of Locust and Chesnut, which, though On the second page preceding the not stately, extends to the east and west, first page of January, at the bottom, the as far as the eye can distinguish such obmean obliquity of the ecliptic, as deter- jects. This vegetable assumes every ap. mined with extreme precision with the pearance of having been one of the originew mural circle, is stated to be 28° 27' nal possessors of the soil. The fewness 50". It should be 23° 27' 50."

of the inhabitants in the valley below, Page 4. On the 13th day of January, and their characteristic lack of energy, Venus is stated to pass the meridian at preclude the idea of its being a naturaliz20 hours. It sliould be 43 hours.

ed stranger, neither have I ever seen it at Page 73. In the column headed any of their farms. “ Other Phenomena," against the 29th Southwest of this place, near the Susday, it is pilt down thus 0 0 ; that is ac- quehanna, the frequency of this tree in cording to the language adopted in the the fields left no doubt in my mind of its Nautical Almack, Venus and Conjunc- being a native. Near the Schuylkill it is tion in conjunction. It should be di cultivated on land which I should judge or Venus 2 Maus in conjunction. equally favourable for its growth, but it is

man.

not scattered over the farms as on the flammatory action, and eventually, if not Susquehanna. The inference from this stopped in its progress, extends itself to fact is, that the roots of those trees, which the sensitive sole, seating itself in the once constituted a part of the ancient heel, and producing an extensive ulcer, forest, have remained unsubdued. In- so much so as to cause a detachment of deed I recollect no instance of young the horny box from the living parts ; plants shooting up in old cleared land which, when effected, is the second stage without the fostering hand of the nursery of the disease. In this second stage, the

disease is seated immediately on the heel, Further, it appears in situations on the inflaming the vascular sole, from which hills north of Pittsburgh, which leaves no ensues an extensive ulceration, producing doubt of its being indigenous ; and sixty a separation of the horn from the sensimiles west of that city, in the State of tive parts. The suppurative process is Ohio, whenever the forest is reduced, accompanied with the sprouting of a lux. and the soil burnt, it springs up in abun- uriant, peculiar fungus, which is with difdance. It will be observed that this is ficulty kept dowli, even by the skilful, considerably north of the Potomac. and entirely bailes the well-meant endea

It will, doubtless, be a satisfaction to vours of those not acquainted with the Dr. Akerly to be apprized of these faets, disease. which, though varying from the informa- In regard to the treatment, the practice tion he had procured, by no means dero- which I would recommend, is to have gate from his general accurracy.

the cattle removed to a dry healthy pasRespectfully, &c.

ture, there to be examined. Such as are DAVID THOMAS. found to be diseased should be taken to a Scipio, 9 mo. 25, 1817.

barn or out-house, and the feet washed

clean, particularly between the cleft, with Ar account of the cause and symptoms of a hard brush and strong suds. In cases

the disease of neat-cattle, called the foot of early standing, as before described, let rot or canker, with the best mode of treat- the diseased feet be immersed in strong ment, by JAMES CLEMENT, Veterinary lye, as warm as the hand can bear, from Surgeon, New York,

five to ten minutes, using brisk friction in The prevalence of a disease attacking the cleft: let a poultice, made of bran, or the feet of neat-cattle, at this season, and shorts, with hogs-lard, be ready, sufficientparticularly in the vicinity of New-York, ly large to envelope the whole foot, which induces me,

for the benefit of agricultur- should be changed twice a day till the acists, breeders, milkmen, &c. to give a few tire inflammation subsides ; dress with outlines of the disease, with the best mild astringents, adding liberal pressure mode of treatment, it being a disease lit- between the phalanges, or divisions of the tle known or understood in this part of foot, with lint, or fine tow, so as to prethe country.

vent their coming into contact. The feet In demonstrating this subject, I laid be- should be wrapped in canvass, and the fore the Lyceum of Natural History, animal kept on a dry floor. Attention preparations of the foot, so as to convey should be paid to the general habits of a more perfect idea of the nature and ex- body: should the inflammation extend up tent of the malady in question, with the the legs, bleed, and give aperient medivarious names under which it has been cine; when extreme pain exists, anotreated. It has been called the Lowe, dynes, administered with discretion, will the Foul, and the Foot-rot, but would be prove beneficial. better denominated Canker. The symp- In the second stage a different mode of toms in the early stage are extensive treatment will be necessary. The aniswelling of the leg, affecting the action of mal being secured, proceed to remove the animal ; great heat and tension ; star- the horn that surrounds the cankered ing of the hair, with a dead appearance; parts, and follow up with a knife so as tholoss of appetite ; wasting of the flesh; roughly to separate the offending parts and in a cow, giving very little milk, so which surround the opening where the as to affect the profit of the owner, and fungus arises. Should hamorrhage take cause inquiry into her condition. On ex- place, as it frequently does, it is easily amining between the cleft of the diseas- checked by touching the part with the ed foot, will be discovereil a thin icho- muriate of antimony, sometimes called, Fous, foetid discharge, exurling from the among farmers, the butier of antimony. superficial blood vessels of the skin.; Should the fungus rise hizaer than the which, from the great vascularity of these surrounding surface, use the knife, 90 as parts, heightens the violence of the in- to bring it on a level; dress with escha"

rotics, adding considerable pressure. The were near neighbours, yet tho curiosity best covering in this case is a compress was in a great measure destroyed, as the of oakum, securing the whole with can- tree, where they deposited themselves, vass. Cleanliness and an entire exclusion was at some distance, and our vier of it of moisture are indispensably necessary. intercepted by other trees. The feet should be dressed once a day, " In Chambersburgh I have obserred and in bad cases, twice. When the ani- the same habits in these birds. They mal is sufficiently recovered to be turned would collect in the evening about sunout, the bottoms of the feet should be down, and pour themselves into my neighcated with tar.

bour's chimney. I have often sat in my The opinion, that this disease arises piazza and viewed them with pleasure, from fulness of habit, is without founda- until my neighbour was apprized of the tion. It attacks fat cattle and lean alike, fact and closed the chimney. This you and is not confined to the fore-feet or the may have an opportunity of viewing any hind-feet. It has been considered epi- summer yourself. demic, having made its appearance for “The reason for finding dead birds and successive years; this is an erroneous bones, is obviously from such numbers opinion. Cattle in upland, where the depositing themselves in the trunk of a soil is dry, are never known to be effect- tree, where the weak must be pressed, ed with it; it is those fed on swampy or and where want of air produces suffocaspringy ground are liable to it. The tion. In chimnies the air being commucause of the disease being thus pointed nicated both from top and bottom hinout, remove the cattle to dry pasture and ders suffocation.” its ravages will cease.

S. B. D.

K.

Messrs. Editors,
TO THE EDITORS OF THE AMERICAN
MONTHLY MAGAZINE,

The following hints on the methods of Gentlemen,

determining the latitude and longitude If the following remarks, (produced by

of places on the land, are respectfully the perưsal of Mr. Wood's observations

submitted for publication in the Amerespecting the swallow,) in your 4th No.

rican Monthly Magazine. Vol. 1. p. 292, from a lady in Chambers- It will readily be admitted by all who burgh, Penn. to her correspondent in this are in any degree acquainted with geocity, should appear useful in helping natu- graphy and astronomy, that it is of the ralists to describe the habits of this spe- utmost importance to the geographer to cies of the feathered tribe, they are at

have the latitude and longitude of seyour service.

veral extreme and intermediate points “Many years ago, while setting in my of a country, correctly ascertained, in orfather's garden at Loudon forge, we no- der to construct a map of the same ticed the chimney-swallows collecting in with precision. And although much has great numbers in the air, and sweeping in a been done in the science of geography, circuit large and wide, past an old hollow by the aid of astronomical observations, locust tree, whose top had been blown it is well known that the great degree off. This excited our curiosity, and in- of imperfection which still remains, is duced us to watch their motions, when more to be attributed to a deficiency we observed them pouring in parcels (fiin- of these observations, than to any other nel shaped) into the tree, and those that cause. Hence we may perceive that it missed getting in, few off in the air, re- would be a meritorious act in the gonewing their circuitous route, and gather-vernment of every country, to employ ing as before, lodged themselves in the persons of competent skill, and furnish same manner until there was not one to them, at the public expense, with suitable be seen, before the twilight closed. This instruments for making correct deterwas continued year after year, and was minations of the latitude and longitude an object of great curiosity, which osten of every important place therein. These, amused both ourselves and our visiters, combined with accurate surveys of the until by the burning of some brush-wood, boundaries, would give to this science in an adjoining meadow, the tree caught a degree of perfection hitherto unfire and was consumed. Their roosting known. place afterwards was in a hollow syca- The most useful instruments for thesa more, on a small island below the house; purposes are an astronomical quadrant, though we had the pleasure to know they a circular instrument of reflection, a parCable transit instrument, a telescope of observation for obtaining the longitude, sufficient magnifying power for observ. find the error of his watch for apparent ing the immersion and emersion of Ju- time, and its gain or loss of time in 24 piter's satellites, and a time-keeper. The hours. The most effectual method of quadrant might be of two feet radius ; doing this will be, by taking the inean the circular instrument of fifteen inches of 5 or 6 altitudes of the sun in the diameter, a refracting telescope of Dol- morning, and afternoon of the same day lond's or Tully's construction, about when the sun bears nearly east or west. four feet in length, of focal distance, with Or, if the sun cannot be observed in a triple object glass of three and three- that position, the lowest altitudes that Burth inches aperture, would answer can be taken. The apparent time is Pery well for the travelling astronomer. used in all astronomical problems exHis transit instrument might be of mo- cept that of determining the longitude derate dimensions, and a watch of the by the eclipses of Jupiter's moons. Be. best kind might serve for his time- cause the time of their immersions and keeper. But since these alone would emersions at Greenwich are given in the form an expensive apparatus, which pre- tables for mean time, the error of the supposes in its use, an accomplished prac- watch must be found for the same at the titioner, acting under liberal patronage, meridian of the observer. This method it seems improper to undertake a de- of determining the longitude of a place scription of the instruments, or to give is one of the most simple, though not the directions for using them. A full descrip- most accurate; but will generally aption of these may be found in Vince's proach so near the truth as to be very and La Lande's astronomy, and the ar- useful in geography. In attempting this, ticle Astronomy in the New Edinburgh the greatest power the telescope will Encyclopedia. We shall only suppose, bear, consistent with distinct vision, that a person of ingenuity, and some pre- should be employed. The observer, acvious knowledge of the theory, should cording to the directions given in the become desirous of exercising his talents Ephemeris, should be ready with his in this way, and being sufficiently inde- telescope at a suitable time before the pendent in his circumstances to expend ingress or egress of the satellite into, or a sum of eight hundred dollars in the out of Jupiter's shadow, takes place. purchase of instruments, and employ And at the instant it happens, must give several months in the year in finding the notice to his assistant, holding the watch, latitude and longitude of a considerable to note the time shown thereby. Then, number of places through which he making an allowance for its error, the should travel for that purpose. With the difference of time between his observaabove sum he might purchase a patent tion and that of the Ephemeris will be lover or horizontal watch, a sextant of the longitude of his meridian, expressed the best construction, contained in a in time. square mahogany hox, which should The simple telescope may also be used, also contain an artificial horizon, and a instead of the transit instrument, for decase of quicksilver to be used in the termining the longitude, by observing same. To these he might add a teles- the time at which the moon's eastern cope, of the dimensions already given. or western limb passes the meridian. The Nautical and Astronomical Ephe. The manner of doing this, and also of meris of the English Board of longitude, observing when an eclipse of the sun or Bowditch's Navigator, and Mackay on moon commences or terminates, are fully the longitude, contain a sufficiency of explained in Mackay's treatise on finding iustructions and astronomical tables for the longitude by sea and land. An eclipse bis purpose. He should also have with of the sun affords the best means for a him the best map of the country or ter- correct determination. That of the moon ritory in which his observations are is attended with some uncertainty ; but made that can be procured, and a case should always be observed with care of mathematical instruments. The map whenever an opportunity occurs. would enable him to find more nearly The lunar method, which consists in an estimated latitude and longitude of observing the angular distance between those places, whose positions would the moon and the sun, or a star, meaotherwise be too uncertain to be made sured by the sextant, and noting the apthe basis of his calculations.

parent time of observation, enables the Our intended practitioner, after being observer to find the true distance, the instructed in the use of his instruments, true time at Greenwich corresponding and their adjustments, must, in every thereto, and consequently, the difference

of time between the two meridians. This In the annexed inethod, if practised with due skill and diagram, let A reprecare, will be attended with success. But sent the sun's place the distances taken will be more success at the mean altitude; ful when not exceeding 100'. And the B, the point of intermean of several results are always pre- section of a perpenferable to that of a single observation. dicular from the sun's

Having nothing more in view than to place to the merishow what may be accomplished by dian; P, the pole, and private individuals who may have leisure 2, the zenith ; PA, and inclination to give their services to will represent the the public in this manner, I proceed to complement of the

B give some hints on the methods of deter- declination ; AZ, the mining the latitude. This is done, both complement of the altitude; and the by sea and land, by taking altitudes of angle, AP 2, the time from noon. the heavenly bodies, chiefly of the sun. The latitude was thus attempted to And the meridian altitude is always pre- be found at No. 331 Broadway, from ferred, because it requires little calcula- 6 altitudes taken, Aug. 26, 1817. Tho tion, and is generally thought to be more horary angle, or time, from noon, was 3h. accurate. When taking altitudes on the 43m. 46.2 sec. ; or, APZ=55° 56' 33" 4; land with a sextant, the artificial horizon the complement of the declination, or becomes necessary. And since the image AP=79° 32' 23" 8; the complement of the of the sun, reflected from the quicksilver, altitude, or AZ=57° 35' 56" 5. Then by is depressed as far below the true horizon trigonometry, Radius : Co-sine of APŽ as the real sun is above it, the index of :: TangentAP:Tangent BP=71° 45'16" 6. the sextant must be moved twice as far, Co-sine AP : Co-sine BP :: Co-sine AZ to bring the two reflected images to- : Co-sine BZ=22° 28''16" 6. BP—BZ= gether, and thereby obtain the altitude, PZ 49° 17', the complement of the laas when it is obtained by using the hori- titude. Hence 90°—49° 17'=40° 43', the zon of the sea. For this reason it will latitude North. be expedient to take the meridian alti- In another trial with four altitudes, tude at such times of the year as it does taken, Sept. 27, 1817, the horary angle not exceed 50°. The angular distance was 36° 5' 15"; the complement of the of the images should not be more than altitude, 53° 34' 39"; the complement of 100°, because a greater angle, as I have the declination, 91° 37' 39" ; and the lati found by experience, will be incorrect; tude resulting, was 40° 42' 59." 9. These and the error appears to be occasioned results, differing only one-tenth of a seby the oblique reflection from the mirror cond, were extremely satisfactory. Beof the moveable index. In my late at- cause the time deduced from the altitempts to find the latitude of this city, out tudes, was believed to be true to the of one hundred altitudes taken between nearest second, and consequently the the 20th of August and 20th of Septem- altitudes must have been correctly taken. ber, 1817, not more than twenty of them But the inean of a great number of reeucceeded.

sults by the other method was 40° 42' 56"; When the meridian altitude has been it was therefore thought best to take the too great to be observed by the sextant, mean of these, and thus the latitude of the following method has been tried, and my plan was settled at 40° 42' 58" N. produced a satisfactory result. Several Great confidence is placed in this last altitudes were taken in the morning, and result. It has been effected by much lathe apparent time deduced from each bour and rigid calculation. But the difseparately. If three, four, or five of these ficulty of arriving within two or three in succession, agreed within one or two seconds of the truth is considerable. If seconds of time, the mean of the alti- the latitude of internal places in general, tudes was then taken, and the time again can be obtained within one minute, or calculated therefrom. Then reducing geographical mile, it will be sufficiently the sun's declination to the apparent correct for constructing maps of large time thus found, the resolution of two territories. But when fixing the position spherical triangles produced the com- of important places, the greatest accu. plement of the latitude. This is recom- racy is desirable. For my own part, I mended in Wallace on the Globes and am satisfied that the latitude of the CityPractical Astronomy, page 165.

Hall, should be recorded at 40° 42' 45" N.

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