Imágenes de páginas


tained in the preceding directions that place, and it was then found were taken by W. Smith, esq., to be running with the astonishing master of his majesty's ship Naiad. rapidity of 99 miles in 24 hours.

(Signed) W. ROBINSON.” On the 10th Sept., at 10 a. m., Inspector-General of Ionian while proceeding in the full Ports and Coasts.

strength of the current, exceeding Corfu, April 1, 1825."

four knots an hour, a sudden and Currents of the Ocean. "In very great discolouration of the the voyage between Cape Mount water a-head, was announced from and Cape Three Points, captain the mast-head: the ship being in Sabine says that the Pheasant's 50 8' north latitude, and 50° 28' progress appears to have been west longitude (both by observaaccelerated 180 miles by the cur- tion), it was evident that the rent, which, in the season when discoloured water could be no other the south-west winds prevail on than the stream of the Amazons, this part of the coast of Western pursuing its original impulse at no Africa, runs with considerable less tha 300 miles from the th velocity in the direction of the land of the river, its waters not being round Cape Palmas, to the eastern yet mingled with those of the parts of the gulf of Guinea. In ocean, of greater specific gravity, the passage between the river on the surface of which it had purGaboon and Ascension, being a sued its course. It was running distance of 1,400 geographical about 68 miles in 24 hours." miles, the Pheasant was aided by Capt. S. continues, “ On a general the current above 300 miles in view of the currents which have the direction of her course. been thus particularized, on the

* * * “ But the more important Pheasant's progress, in her voyage distinction, both in amount and in commencing at Sierra Leone and utility in navigation, is between terminating at New York, it may the waters of the Equatorial and be seen that she was indebted to the Guinea currents. These ex- their aid on the balance of the hibit the remarkable phenomenon whole account, and in the direction of parallel streams, in contact with of her course from port to port, each other, flowing with great not less than 1,600 geographical velocity in opposite directions, and miles, the whole distance being having a difference of temperature under 9,000 miles; affording a amounting to ten or twelve degrees. very striking exemplification of the Their course continues to run importance of a correct knowledge parallel to each other, and to the of the currents of the ocean, to land, for above 1,000 miles ; and, persons engaged in its navigaaccording as a vessel, wishing to tion; and consequently of the proceed along the coast in either value of the information, in

, direction, is placed in the one or the acquisition and arrangement the other current, will her course of which major Rennell has passed be aided from 40 to 50 miles a-day, the latter years of his most useful or retarded to the same amount. life. The publication of the charts On the day after the Pheasant of the currents in the most fresailed from Maranham, she entered quented parts of the occan, which the current, the full strength of he has prepared with his accustomwhich she had quitted to go to ed and well-known indefatigable Vol. LXVII.



[ocr errors]

assiduity, and strict adherence to given on the 22nd is only approxithe evidence of facts, (as soon as mate ; it will, however, be amply he shall deem them sufficiently sufficient to enable observers to complete), will be a most impor- find it. It is visible in a night glass. tant service rendered to practical navigation.”

The Second Comet, or the Comet Meteor..Guelderland: The

of short period. rains we had in August have con

August 21, 1825. tributed much to the improvement Right Ascension 7h 53 29.31"

At 1h 39' sídereal time. of the crops in general, especially Declination . 28° 40' 24.45" N. after the great and intolerable heat

August 22, 1825. of which I gave you an account in At lh 39' sidereal time. one of my former letters. In the Right Ascension 8h 1' 29.16"

28° 9 56.78 N. latter end of August, a singular Declination aerial phenomenon took place at

This Comet also has no appear11 o'clock in the evening, viz... ance of tail; its observed place very considerable blue light was differs so little with that given in seen, which gave a most extra- Eicke's Ephemeris, that by placing ordinary appearance to all sur

the instrument according to the rounding objects ; so much so, that data there given, the Comet will be notwithstanding it was a full easily found. It is not visible in moon, and fine clear weather, it so the night glass, yet it is much more frightened the servants, who were distinct than the preceding Comet. standing in the garden behind our Passy, near Paris, Aug. 23, 1825. house, that one of them came Aurora Borealis. A late running into our room, in the number of the Edinburgh Philogreatest state of alarm, to mention sophical Journal contains a memoir the circumstance. The same ap- by professor Hansteen, in which pearance was noticed at the very thateminent naturalist has sketched moment through the whole coun- out a very bold and plausible try, which proves that the substance theory of the Aurora Borealis. The or combustible fluid which emitted connexion of that phenomenon it must have been at a great eleva- with magnetism has been long tion.”

remarked, and is further confirmed Two Comets.-The following by the observations of the profesare particulars of_two Comets at He considers the Aurora present visible in Europe

Borealis as a luminous ring surThe First Comet.

rounding the magnetical pole, with

a radius varying from 20 deg. to Observatory, Pasey, Aug. 21, 1825.

40 deg., and at the height of about Sidereal time at Passy. Rt. Ascen. 4h 15' 2.96" at 23h 36' 18''

one hundred miles above the surDeclina. 21° 40 50.07 N. at 23 43 43 face of the earth. It is formed, August 22, 1825.

he thinks, by luminous columns

shooting upward from the earth's *Right Ascension 4h 14' 49"

surface, in a direction parallel to Declination ... 21° 26 0 N.

the inclination of the needle, and This Comet has no visible tail, to the direction of the earth's is very faint, and has the appear- magnetism : these columns render ance of a Nebula. The place on the atmosphere opaque while they the 21st is tolerably exact ; that pass through it, and only become



At 1h 1' 36" sidereal time.

luminous after they pass beyond it. the standard during Dr. Tiarks' From the outer or convex side of survey to ascertain the longitude the ring beams dart forth in a of Madeira in July and August, direction nearly perpendicular to 1822 ; and its accuracy during the the arch, and ascend towards the time it was under his care induced zenith ; and if they are so long as him to take the longitude of Mato pass it towards the south, they deira from it. Dr. Tiarks takes collect in the south in a sort of the mean of the whole 16 chronocorona or glory, which is situated meters employed on the occasion, in that point of the heavens to by interpolation; and the standard which the south pole of the needle gives the same result as the whole points. Professor Hansteen finds 16, within two hundredths of a that the observations made respect- second. It appears that through ing the Northern Aurora are well the means of these chronometers, explained by this hypothesis ; and Dr. Tiarks has been enabled to he has collected facts to show that discover a considerable error in the a similar ring exists around the longitude of Madeira (as laid down southern magnetic pole situated in by a former survey), and to find New Holland, the northern being out where the errors lay.

He was in North America. He infers employed by the Admiralty, at the further, though the stock of obser- recommendation of the board of vations is rather deficient, that Longitude, in 1823, to find, by the similar luminous rings exist above use of chronometers, the differences the two extremities of the secondary of longitude between Dover and magnetic axis, in Siberia, and in Falmouth, and Portsmouth and Tierra del Fuego.

Falmouth; and for that purpose he Chronometers.—The official re- was furnished with 29 chronoport from the board of Longitude meters from the royal observatory, of last year's trial of chronometers including all that were on trial for has been published. The annual the prize. On this survey, he has prize of 300l. has been awarded to discovered an error in the longiMr. W. Widinham, of East-street, tude of these important stations, as Red-Lion-square, for the best chro- laid down by former surveys, in nometer, it having varied only 1 consequence of the accurate rate of second and 80 hundredths of a going of these chronometers. He second on its mean daily rate during has thus been enabled to establish the 12 months. The prize of 2001. the following results :-Longitude has been awarded to Mr. J. M. of Dover station, 5 min. 17 sec. French, of the Royal Exchange, 54. E. ; Portsmouth Observatory, for the second best chronometer, 4 min. 24 sec. 77. W.; Pendennis: his having varied 1 second and 85 Castle, 20 min. 10 sec. 85. ; Mahundredths of a second during the deira, 1h. 7 min. 39 sec. 08. On 12 months; 85 hundredths of a this occasion, also, it appears that second during the last 9 months; Mr. French's chronometer was the and 45 hundredths of a second standard. The former survey had during the last six months, on its placed the longitude of the two mean daily rate. Mr. French's latter places about 4 seconds less chronometer, No. 720, was made to the westward.


It was

[ocr errors]

Natural Sources of Carbonic washed, was dried in a WedgeAcid Gas.—Bischoff and Nögge- wood's basin, at a temperature aprath, in Schweigger's Journal, proaching 300°, until so dry as not mention a pit on the side of the to render a cold glass plate, placed Lake of Laach, in which they over it, dim. Being then stirred found many dead animals, as birds with a platina spatula, it in a few of different kinds, squirrels, bats, moments, by friction against the frogs, toads, and also insects. On metal, became so strongly electridescending into the pit, and gradu- cal, that it could not be collected ally sinking the head, they expe- together, but flew about the dish rienced the same sensation as when whenever it was moved, and over held over a vat in a state of fer- its sides into the sand-bath. It mentation. The quantity of gas required some little stirring before evolved varies at different times. the particles of the powder were This evolution of carbonic acid gas all of them sufficiently electrical is more striking in the volcanic to produce this effect. Eifel. On the right bank of the found to take place either in porriver Kyll, nearly opposite to Bir- celain, glass, or metal basins, and resborn, there is a spring named with porcelain, glass, or metal stirBrudelreis ; a provincial name for rers; and, when well excited, the a boiling spring, and applied to electrified particles were attracted this because it is perpetually agi- on the approach of all bodies, and tated by large bubbles of gas, the when shaken in small quantity on agitation being so great as to pro- to the cap of a gold-leaf electroduce a noise heard 400 yards off. meter, would make the leaves diIn its vicinity numerous dead birds verge two or three inches. The are found, killed by the carbonic effect was not due to temperature, acid rising from the water; and for, when cooled out of the contact persons who kneel to drink at the of air, it equally took place when spring are driven back by the gas. stirred; being, however, very hyAs MM. Bischoff and Nöggerath grometric, the effect soon went off approached this spring, they heard if the powder were exposed to air.

. the noise of its ebullition at a con- Excited in a silver capsule, and siderable distance, and by approach- then left out of contact of the air, ing their faces to the surface of the substance remained electrical the turf in the vicinity of the a great length of time, proving its spring, found that it was covered very bad conducting power; and

, with a layer of carbonic acid gas. in this respect surpassing, perhaps, They did not observe


delete- all other bodies. The effect may rious effects produced on the sur- be produced any number of times, rounding trees


On and after any number of dessicaemptying the basin no more water tions of the salt. Platina rubbed was collected, showing that it was against the powder became negarain, not spring water.

tive--the powder positive; all Electric Powers of Oxalate of other metals tried, the same as Lime. Some oxalate of lime, ob- platina. When rubbed with glass tained by precipitation, when well- the glass became strongly negative,



the oxalate positive, both being lowing brief extracts of the expedry and warm.

rimental results which it contains : Metallic Titanium in Iron Fur- fourteen parts of nitric acid of spenaces.--Cubic crystals of metallic cific gravity 1.430 and one part of titanium, similar to those discover- Guatimala indigo were distilled ed by Dr. Wollaston in the iron together; about a fourth part of furnaces of South Wales, have also the new acid was obtained with a been found by Dr. Walchner, of small quantity of yellow bitter Friburg, in the Breisgau, in the substance. Repeated washing in founderies of the highlands of alcohol and distilled water separatBaden. The piece of slag examin- ed this substance, and the acid dised was from the high furnace of solved in boiling water and crystalKandern, in which pea iron ore lized by cooling was obtained pure. only is smelted. Being desirous The acid is always of a yellow of ascertaining the presence of the colour, of a bitter taste, crystalline, titanium in the pea-iron ore, an

soluble in water, and when placed attempt was made with the blow- upon a hot coal deflagrates somepipe, and its presence, Dr. Walch- thing like nitre. Combined with ner says, was indicated, though in potash, soda, ammonia, baryta, and very small quantity.

lime, it formed neutral salts, all of Polarized State of Halo Light, which are described as fulminating. -M. Arago very lately announced, In consequence of the suspicion that upon examining a halo round that it might be benzoic acid, Berthe sun towards 11 o'clock in the thollet, Fourcroy, and Vauqueline, morning, with an instrument of having said that benzoic acid is his invention, he remarked very formed by the action of nitric acid unequivocal traces of polarization on indigo, it was compared with

, by refraction in the light of which that substance as to solvent power, the halo was formed. This expe- &c. and found to be essentially riment excludes all explications of different. the phenomenon founded upon the Analysis of the Strong Saline hypothesis of a reflexion. M. Water from a Spring in Windsor Arago thinks that the instrument Park. This water is transparent he made use of in this observation and colourless, and affords no indiwill enable him more generally to cations of the presence of iron. Its ascertain when a cloud is frozen, specific gravity is 1010:4 : one pint and that it will then supply the (of 7,000 grains) left, after careful means of studying the law of the evaporation, 88 grains of dry saline diminution of heat in the atmos- residne. By the action of tests, phere.

the following substances were deMoretti's Fulminating Acid.- tected in the water, and in the On occasion of the late experiments annexed proportions in the pint:made by MM. Liebeg and GayLussac, on fulminating compounds,

1. Sulphuric acid

33.00 &c. the Giornale di Fisica has re- 2. Muriatic acid published the account of an acid 3. Carbonic acid also possessing detonating proper

4. Magnesia

21.25 ties, prepared as far back as 1808,


21.00 00.98

10.52 6. Lime......

1.25 by Professor Moretti, from indigo, by nitric acid, We make the fol

Total contents .... 88

5. Suda ...

« AnteriorContinuar »