Herts Hants To the Editor of the Monthly Magazine. SIR, As S your excellent Miscellany has an extensive circulation on the continent of Europe, the information which I here transinit, may be likely, by its means, to meet the notice of the friends and family of the unfortunate ROENTGEN, whose fate, this communication records. He arrived at Mogadore in the Spring of 1811; and, in consequence of letters of recommendation from Sir Joseph Banks, Mr. Mitford, and Mr. J. G. Jackson, resided at my house. I was not at home at his arrival, and but a very few hours during his stay in Mogadore, as I arrived home on the Friday noon, and he set off on his journey for the interior early the next inorning. His first intention was, to have remained one year at Mogadore; but, making a journey to Morocco about two months after his arrival, he soon after. his return became extremely impatient to commence his very arduous undertaking. The plan which had been recommended by me was, to engage some trader going to Tombuctoo to take him under his protection, and bring him safe back for a stipulated sum; but this proposal carried with it too much the air of restraint. I had had in my service for about a year prior to Mr. Roentgen's arrival, a man born at Beverly, in Yorkshire, of German parents. This fellow, when a seaman on-board a British ship of war, which put into Tetuan or Tangier, ran away, and turned Moor; had been a renegade some years, and was in my With this man, employ as gardener. Mr. Roentgen unfortunately contracted a very close intimacy; which originated, no doubt, from his talking the same language, and the fellow's parents being natives of the same part of Germany as Mr. Roentgen, He therefore determined to take this renegade for his companion; and, on my arrival at home, I found them ready to set off. I endeavoured to persuade Mr. Roentgen to put it off for a few days, as I did not like his trusting wholly to a renegade; but he said things were gone too far; the man was in possession of all his plans, and one day's delay might be fatal. Southampton, Agmondesham, and the three next, had discontinued this privilege from 28 Edw. I., Anno 1300, to 21 Ja. I., Anno 1628, being 323 years; when a search by Mr. Hakevill, of Lincoln's-inn, into the Parliamentary Writs in the Tower, terminated in the restitution of their suspended rights, in consequence of a petition to the House of Commons, and a report of their committee adopted by the House: upon which warrant from the Speaker, the Clerk of the Crown in Chancery was directed by his Majesty to issue Writs of Election for these several boroughs.* I may probably trouble you hereafter with the state of the present population in some, at least, of these places. It might be obviously possible greatly to ameliorate the present representation, by restoring and modifying the elective franchise in these boroughs, adding to them (as in the case of Shoreham) a suf. ficient number of votes from the surrounding hundreds, though I think it ought to be greater than in that instance, And, whether there be power by prerogative of the crown or not, to create a new borough; the right of election once exercised cannot be lost by disuse: though, for the public good, Parliament may extend it to a greater number. to the equilibrium secured to the Scotch and Irish nation by the Union, a simple application of the Rule of Three solves that difficulty, with addition of few members for each. As very CAPEL LOFFT, Troston, Dec. 6, 1812. Mr. Roentgen was accompanied out, the first fifteen miles, by several Euro * Pret. to Glanville's Rep. lxxxix. xcvi. peans, who returned in the evening. and the Reports 87-96. One remained the night with him, ayd the Mr. Court on the Fate of Roentgens 1815.] the next day until they reached the, River Tansif, where Mr. Roentgen suuk his European clothes in the river, and put on the Moorish dress; and he then pursued his journey, accompanied only by the renegade. They were provided with two good mules, a variety of beads, and other articles of merchandise; about five hun dred dollars in money, and each well armed with pistols, swords, muskets, and daggers. Mr. Roentgen was also well supplied with drugs to pass as a physician when it might be necessary in the interior. He carried with him also a very fine copy of the Alcoran, on vellum, which night be of service to him in gain ing the protection of some sheriff. At parting, Mr. Roentgen promised we should hear of him by every opportunity, if only his name, date, and place, on a bit of paper. We, however, never heard from him. apparently belonging to an European; and the rumour inmediately went forth, that they belonged to Mr. Roentgen, who had been murdered. The governor of this place sent for the articles from Morocco, and they were all identified as having been Mr. Roentgen's, by my brother, and the watch, as one which he always wore suspended by a ribband from his neck. There was now but too much reason to suppose this unfortunate traveller had been murdered, and that within three or four days' journey of this place; but still no one suspected the renegade. We sent to Morocco, to have the examination of the Moor taken. He persisted in declaring that he found Mr. Roentgen dead, and in a very putrid state, under a tree; and that he took from his person the various articles which he had offered for sale. About seven months ago, I received intelligence that the renegade had been seen at Arzilla, a town about 300 miles to the northward, where he was working as a gardener, and that he was going to Oran to embark for Europe. Upon sending to Arzilla, however, I could not find him, or ascertain to a certainty that he had been there. A month afterwards, a Jew who came from Mequinez told me, he saw him in that city, and spoke to him; and that the renegade was very shy of speaking to him. There is, I think, little doubt but Mr. Roentgen was murdered by the man in whom he placed his entire confidence; and that man an European! The mules, the dollars, and the various articles with which the mules were loaded, were sufficient plunder, without taking the few articles from his person, which were of little value. It is probable, too, that although the wretch could murder his master when asicep, he might not have the courage to strip him afterwards. As Mr. Roentgen had taken uncommon pains to make himself fit for undertaking such a dangerous journey as to the interior of Africa; and, as he was a young man of considerable talents and of great. perseverance of mind, it is very much to be lamented that he should have met with such an untimely end. As a number of letters have been addressed to him at my house, the writers will have them returned, on signifying their wishes to that effect. A. W. COURT. Mogadore, October 20, 1812. To the Editor of the Monthly Magazine. SIR, AVING been in a calcu Hlation of the great solar eclipse that will happen in 1820, and conceiving that some account of the same might not be uninteresting to many of y your astronomical readers, I am induced to solicit a corner in your very instructive and entertaining Miscellany. This eclipse will not be total, even where it is central, for, the moon being near her apogee, or at her greatest dis tance from the earth, her apparent se midiameter will be considerably less than that of the sun, leaving an annulus, or ring, of light, of nearly half a digit in breadth. The annular boundary will pass very near the eastern shores of England and Scotland; and, on the coasts of Norfolk and Suffolk, this eclipse will be almost annular. The central tract will commerce in latitude 81° 43′ N., longitude 149° 49′ W.; passing over Mayne's Island, to the western coast of Norway, along the B 2 North North Sea, and entering Germany, not far from the mouth of the Weser, crossing that country to Trieste; thence down the Gulph of Venice, into the Mediterranean Sea; and, passing near Cape Matapan and the Isle of Candia, it leaves the Mediterranean to enter Palestine: passing between Jerusalem and Gaza, it quickly enters Arabia, where it quits the earth, with the setting sun, in latitude 27° 15′ N., longitude 46° 9′ E. But the penumbra will first touch the earth in latitude 59° 40′ 38′′ N., longitude 91° 5′ 5′′ W. and finally leave it in latitude 3° 20′ 33′′ N., longitude 20° 28′ E. Owing to the great northern latitude of the moon, this eclipse will not extend farther south then latitude 13° 26' S., longitude 32° 6' E. But the penumbra will pass far above the earth in the other hemisphere. At all those places where the digits eclipsed are 11, the obscuration will be as great as where it is central, for the whole of the moon will, in such case, appear upon the disc of the sun. The sun will be central eclipsed on the meri. dian, in latitude 77° 20′ 43′′ N., longitude 16° 37' 45" W. The centre of the penumbra will be 2h. 13m. in passing over the earth, and the whole duration of the general eclipse, or the time of the penumbra passing over the disc of the earth, will be rather more than five hours and a quarter. The apparent time of the true conjunc tion is September, 7d. 1h. 51m. 27.2s., at which time the true longitude of the sun and moon is 5° 14° 47′ 41′′ (happen ing only 43′ 14.6" east of the nonagesi mal degree) with the moon's true latitude 44' 37.9" N. descending the borary motion of the moon in latitude 2' 41.94" and in longitude from the sun 27′ 158"; the horizontal parallax of the moon from the sun reduced to the radius vector, for the given latitude is 53′ 40·08". Hence the longitude of the sun and moon at the visible conjunction is 5° 14° 47′ 37′8′′; and the apparent latitude of the moon 3' 10.73" N. At the time of the greatest obscuration, the angle of the moon's visible way from the sun is 16° 56′ 16′′; and the nearest distance of their centres 3' 2'45". Now the apparent semidiameters of the sun and moon are 15′ 54.81′′ and 14′ 51.93"; hence the parts deficient are 27′ 44-29", and the digits eclipsed 10° 27′ 30.1" on the sun's upper limb; or 17° 18′ 22′′ to the east of the vertical point of his periphery; at the same time, the longitude of the nonagesimal is 5′ 14° 20′ 23′7′′, and its altitude 39° 1' 18'3"; the parallax of the moon in latitude 41′ 39-72" and longitude 16-647". The moon is on the nonagesimal at 1h. 55m. 14s. or about 2m. 26s. after the time of the greatest obscuration at Greenwich. After giving this outline of the general eclipse, I shall proceed to the calculation of it for the latitude and meridian of Greenwich; but let me premise, that the places of the sun and moon are computed with the greatest care, and from the best astronomical tables. Moreover, as the accuracy of all computations regarding solar eclipses, depends entirely upon the nicety observed in obtaining the parallaxes of the moon, I have been particularly careful on this head; and, not wishing to confide in any auxiliary tables, I have computed the parallaxes from the triangles themselves; for, in the present instance, the conjunction happens so very near the nonagesin al degree, a greater exactness was required, owing to the curvature of the apparent orbit; and I have ascertained no fewer than ten points of the segment of the said orbit, which is described during the time of the visible eclipse at Greenwich, so that the beginning, middle, end, and digits eclipsed, will be found to agree with the best observations to a surprising degree of exactness. At the beginning of this eclipse, the apparent latitude of the moon is 12′ 11.3 N., and her visible difference of longi tude from the sun 28′ 17-27"; the moon's apparent semidiameter is 14′ 53′28′′, and the point of contact of the sun and moon's limbs is 49° 9' 54.3" to the west of the sun's upper limb. But, owing to the moon's decrease in latitude, and the position of the nonagesimal at the time of emersion, the apparent point where the moon's limb quits the sun is 86° 56′ 0′′, to the east of the zenith of his disc when the moon's apparent semidiameter is 14' 49.88"; the apparent latitude of the moon 5' 20" and the difference of longitude 30′ 17′′. 5 rule, page 58, that (by Mechanics) the weight of the semi-arch is to its pressure, in the direction M A, as N M is to MA, -see the figure. As the tract of this e 41.94 incipally confined to Europe, er, namely nk that an accurate delineatise co Sematish of the penumbra, engraved pon a map of that quarter of the world, would not be uninteresting to many curious persons, who could then see, at one view, the progress of the greatest eclipse we shall have in these parts, for many years to THOMAS SQUIRE. 1812. come. Epping, Dec. 30, B To the Editor of the Monthly Magazine. SIR. I SHALL once more, with your permission, occupy a small portion of your valuable Magazine, with a few observations on a similar subject to what I have heretofore. But the author, from whom I now venture to differ in opinion, is so far my superior in physico mechanical acquirements, that it is with the utmost diffidence I enter upon the task, although, from an attentive exami nation of the subject, I am persuaded that I have truth to support ine; and, being thus supported, I am encouraged to proceed, notwithstanding the great disparity above-mentioned. Dr. Hutton, in his Principles of Bridges, Sec. iii. Prop. x. has, as it ap pears to me, fallen into more than one error. For, first he lays it down as a M GEL Now, with all due deference to those superior acquirements, I contend, that Mechanics will not bear him out; for a line, drawn from N to A, will not meet the angle of abutment at right angles to it, which is required it should do by Mechanics; neither will this line be in the direction of the initial pressure, for a line in that direction will be a tangent to the arch, as the line Na. Besides the line NA intersects the curve, and is a chord to part of it above A, instead of a tangent, and consequently can no-where, within the limits of the voussoir, meet a radius of curvature at right angles. But the line Na is a tangent to the curve, and consequently in the direction of the initial pressure, and the radius of curvature V B, at the point of contact, is at right angles to it; and then (by Mecha nics) this radius of curvature would be virtually the angle of abutment, which must be transferred, or supposed to be, to the pier at a, where this line intersects the vertical line IL, or face of that pier, and that intersection will be the height of the same to calculate from, as will the vertical distance from thence to the line D N, continued N m, be the measure. of the vertical pressure for that purpose; and from those measures, together with the area of the semi-arch 809, the effi cacious force of the arch, to overset the `pier, may be obtained by the rules given in that work. Secondly, the whole resistance of the pier is there stated to be only what will arise from the multiplication of its area, into into half its thickness, that is, GLX FE XEG. But, with the same respectful deference as before, I again contend, that the sum of this resistance is equal to GLX FEX EG+ LG X area of semiarch; for, as the weight of the whole arch and covering must act upon the inside faces of the two piers, the weight of the semi-arch must act upon the inside face of one; and, this being admitted, I shall refer to Example the second, in the same proposition, and compare results. By the admeasurements, as there set down, the distance of the centre of gravity from D, or DN, is 33.58 feet, which answers to the tangent of 33° 15' of the curve D A nearly, and consequently the other tangent in the direc. tion of the initial pressure being the same from the point of contact at B to N, the whole quantity of the curve to be considered as an arch, is 66o 30'. But the whole curve, from the apparent angle of abutment at A to D, is 77° 20′, and 77° 20′ - 66° 30′ 10° 50′, a portion of the curve, which cannot be pro perly considered as part of the arch, in determining the thickness of the piers. It will be found by calculation, that the distance between the apparent and virtual angle of abutment, will be equal to 2.24 feet; therefore the height of the pier to calculate from, will be 18+2·24 20 24, and N M 40—2·2437.76, Nm. MA 16'42, and area 809, remaining the same. Then, from those data, and the whole height of the pier =64, its thickness may be deduced, and it will be found to be 6912 feet, little more than half the thickness of Dr. Hutton's pier, which is 13.67 feet. Notwithstanding, the efficacious force of the arch is greater by our method than by 809 × 16:42 his: for by our's it is 37.76 20.247120 432, and by 809 × 16.42 -X 18-5976. 40 Such opposite differences in cause and effect almost staggers belief, and, upon merely a superficial view of the subject, refuses its assent, to what I conceive to have been made sufficiently clear; and those doubts will be further strengthened when we recollect that the second edition of Dr. Hutton's work was published after a lapse of twenty-nine years, from the publication of the first; and at a time when the Commons of the United Kingdom had applied to him for his opinion upon the subject. This, together with his well-known abilities as a mathema tician, would have induced me also to think I was wrong, were I not convinced, both by theory and practice, that I am right. But we are now both before a discerning public, and it is for them to decide. his Here, Mr. Editor, I shall close this subject, and likewise our correspondence, for the present, as I know of nothing more that appears to me very reprehen sible, or likely to mislead my brother bridge-builders in their pursuit to attain knowledge in their profession. But, if time and other circumstances will permit, I intend in another shape to furnish them with every information I am capable of affording them, both in theory and practice. And now, with thanks for the indulgence I have received from you, I conclude. JAMES PARRY, Bridge-builder. 10qs 1 To the asdf the Monthly Magazine. HA & I too much gratified with the al is 5' 1 ng account of the Honour9° 1' 18 Cavendish, in your Num be in latituer last, to be inclined to fee 16-647". ith it; but there is one sesient at chat memoir which is cal culated to make a wrong impression, and which a desire to do justice to my excellent friend, Dr. Hutton, induces me to correct. The assertion to which I advert is, that, at the top of column 2, page 421, where the deterinination of the mean density of the earth is ascribed to Dr. Maskelyne, and no mention whatever is made of Dr. Hutton, though he was undoubtedly the first person who ascer tained that point. Had Dr. Maskelyne been living, I am persuaded that disXtinguished astronomer, and truly atniable man, would not have suffered so mistaken an assertion to pass without correction: but, as he has passed to other regions, and higher employments, and as Dr. Hutton is, I believe, too much en gaged in other concerns at present to enforce his own claims, perhaps you will indulge me with the insertion of the following hasty sketch of the leading proceedings relative to the matter question. In If the attraction of gravity be exerted, as Newton supposed, not only between the large bodies in the universe, but between the minutest particles, of whicha those bodies are constituted, it becomes exceedingly probable that the irregula Filie's |