ent ways, and independently of each other. One series is to be made with meridian instruments at stations, as remote from each other in latitude as practicable, and will consist of differential measurements of declination between Venus and the brighter stars near its path, which are visible in the day time. To render these available in the question of parallax the distance between the observatory at Washington, and the proposed station in Chili, will afford an ample base of 6,000 miles. The other embraces differential observations out of the meridian, more particularly in right ascension, and which in cases of the planet's near approach to any star, can be made with the utmost nicety. A few instances of near approach to some of the brighter stars may be selected, when the two bodies can be followed throughout the day, and in such cases, full series of observations with an equatorial instrument, would be among the most valuable for the proposed object; and their value would be increased by combinations with others of a similar kind at other and remote stations.

For such observations it is proposed to occupy some point in Chili, as an astronomical station. So far as they may be available in the determination of the Solar parallax, or even for the confirmation of previous determinations, they will be of the highest interest. But apart from this primary object, the expedition and observations contemplated, commend themselves on other grounds to the warm interest of all astronomers and lovers of science. The perfection of these observations will require others upon other objects and the whole will be a just tribute of America, and American astronomers, to to their co-labourers in a science to which our country is largely indebted for the prosperity of some of its most important interests. No such expedition has ever returned without rich fruits, even of different kinds, and gleaned from different fields from those for which it was originally designed.

The fact that a quantity, so essential to our accurate knowledge of the Solar system as the Sun's parallax, should rest for its determination on observations of a single phenomenon, the transit of Venus in 1769, is suffici ently indicative of the high value of the proposed measure. So important for this purpose in the eyes of astronomers, were deemed this transit and the previous, but inferior one in 1761, that we find them scattering themselves over all parts of the habitable globe, wherever the phenomena could be advantageously observed. In 1761 they occupied stations from the remotest regions of Siberia to the southern extremity of Africa, in the wilds of Arabia, and on the islands of the Indian Sea. In 1769 even with greater zeal they were scattered over Europe, America, and the South Sea Islands, to observe one of the rarest and most interesting and important phenomenon, which the annals of astronomical science afford. Not only the learned societies, but the governments of Europe encouraged and aided this laudable undertaking, and even in that day American astronomers, shared in the labours, and reaped their portion of the honours of the great occasion; yet the zeal of all was not rewarded with success. Unfavourable weather at some of the most important stations either seriously impaired or entirely prevented observations. At others the observations have been regarded with suspicion, deserving but little confidence. And the distinguished Encke who has given the most thorough, and scrutinizing discussion of all these observations, although he assigns to his resulting parallax the small probable error of 0.05, yet near the close of one of his admirable treatises on the subject remarks, that had the weather been favourable at all eight of the northern stations in 1769, and had as many astronomers stationed themselves at the different points of the Friendly Islands, their 16 observed durations alone would have afforded a more accurate determination of the parallax, than the whole 250 equations of condition derived from both transits. But compared with the

or as

transit of 1769, he speaks of the two next transits, those of 1784 and 1882, as unfavourable for this purpose, "presenting disadvantages which even the perfected state of instruments will not fully counterbalance"; and in view of the extremely rare occurrence of these phenomena, and of the unfavourable character of several succeeding ones, he intimates that for 3,000 years, the transit of 1769 may remain as the chief means from which we are to derive our knowledge of the actual dimensions of the Solar system. At any rate it will not be before 1874, that astronomers can avail themselves of a transit of Venus, for even an imperfect verification of Encke's parallax, and centuries will elapse before the occurrence of one so favourable as 1769. But even for the expiration of these 26 years, the rapid advance of science will not permit them patiently to wait. The progress of astronomy, and the interests of navigation require an earlier confirmation and redetermination of a quantity so important; and astronomers will watch with deep interest the accumulation of observations which bear upon this point; and which if even less perfect in themselves separately, will yet finally by their numbers, and the variety of circumstances, under which they shall be made, be entitled to weighty consideration.

Two methods have been suggested: one by observations on Mars, which has only been partially tried, and with but partial success; the other, the one which it is now proposed to attempt, and which offers a decided advantage in the greater proximity of Venus to the earth. It has been proposed to astronomers, from a respected and distinguished source. It comes to us recommended by other names of high authority, and by two learned bodies of our own land-the American Academy of Science, and the American Philosophical Society.

But, although, the proposed expedition of Lieut. Gilliss is for carrying out chiefly the latter method, it need not, and will not preclude the other; and the various other observations he will be able to make during the two years he proposes to devote to this work, will furnish a rich and valuable series, from which alone, entirely apart from the consideration of his main design, astronomers and scientific men in other spheres have applauded and warmly commended his purpose.

But, the main design itself is not without the highest prospect of success. The committee are informed by practical astronomers, that, taking for example the proposed meridian observations, with the nice constructed instruments of the present day, and good observers 0''7, would be a large estimate of the probable error of each observation. The probable error then of the solar parallax deduced from such observations, at stations as distant as Washington and the proposed position in Chili will be 03 to 07, according to the distance at the time of Venus from the earth; and, the error of the result from an accumulated number of such observations may be rendered very small, provided no constant uneliminated error remains, which will be common to them all. But, the liability to such error can be greatly diminished by the skill of the observers, and their careful attention to all circumstances which may affect their problem; and, this liability to error will be still further diminished by combining the results of the meridian series with those from the extra meridional observations contemplated, and which will have been made under far different and more variant circumstances. These common errors, the computation of probable error does not include, and it may be doubted whether the resulting parallax of 1769, is wholly free from the effects of such. Astronomers aim even that their results should be deduced from observations as extended, made under circumstances as varying, and with means as different as possible; and, in this respect, the determination of the solar parallax, as yet stands almost alone, as the result almost of a single phenomenon.

THE CALIFORNIAN MANIA.

THE earliest accounts we have met with of the discovery of gold in California, are preserved in "Burney's Collection of Voyages in the Pacific." It has been asserted that, the discovery was made in the middle of the last century; and, Capt. Shelvocke is also stated to have first found it a century and a quarter ago. Burney has, however, preserved an accouut which we quote here of the discovery of it, by the early Spaniards, in 1539, just 20 years after Cortes landed at Vera Cruz. That the existence of the rich district was known, is, therefore, evident, although its exact locality remained locked in secrecy, limited no doubt, but not to those who had contemplated the Mexican war, and its intended results. Burney has preserved the history of the journey of Friar Marcos de Niza, containing the account to which we allude.

"From Petatlan, Friar Marcos de Niza, with his followers, travelled along the coast, where people came to him from islands; and, he saw some that came from the land where the Marquis Cortes had been. At the end of a desert of four days journey, he found Indians who had not knowledge of the Christians, the desert obstructing communication between them and the countries to the south.

"These people," says the friar, "entertained me exceeding courteously, gave me great store of victuals, and sought to touch my garments, and called me Hayota, which, in their language, signified ‘a man come from Heaven." The principal motive of this undertaking, however, was not one of a pious or spiritual nature. It was to spy out the land, whether it was good or bad, and to bring of the fruit, that his countrymen might know if they should go up and possess it.

"These Indians," says the friar, "I advertised by my interpreter, according to my instructions, in the knowledge of our Lord God in Heaven, and of the Emperor. I sought information of other countries, and they told me that four or five days journey within the country, at the foot of the mountain, there was a large plain, wherein were many great towns, and people clad in cotton. I shewed to them metals which I carried with me, to learn by them what rich metals were in the land. They took the mineral of gold and told me that thereof were vessels among the people of that plain; that they had thin plates of gold, wherewith they scraped off their sweat; that the walls of their temples were covered therewith, and that they used gold in all their household vessels.

"I sent Estevanico another way, and commanded him to go directly northward, to see if he could learn of any notable thing which we sought to discover; and, I agreed with him, that if he found knowledge of any people, and rich country, which were of great importance, he should go no further; but, should return in person, or send me tokens: to wit, if it were a mean thing, he should send me a white cross, one handful long; if it were a great matter, he should send me a great cross, &c."

Estevanico, in his new route, very soon received information concerning the seven cities, and that the nearest was Cevola, which was said to be distant thirty days' journey. Towards Cevola, Estevanico directed his steps, sending messengers to the father; who, the fourth day after their separation, received from him “ a great cross, as high as a man." At the sight of this

*Herrera mentions the same distance. He writes the name Cibola. Dec. 6. 1. 7. c. 7. Ortelius, in his chart, No. 5. America, Sive Novi Orbis, places Cevola m 36° north latitude, and about 7° of longitude east, from the mouth of the river Colorado. Theatrum Orbis Terrarum. Edit. 1584.

token, and on hearing the reports of the messengers, Friar Marcos set forward, following the steps of his intelligencer. The friar relates that, in this journey, by a small deviation from a direct route, he came in sight of the sea coast, in 35° north, which he saw stretched from thence to the west. Giving him credit for speaking to the best of his knowledge, it cannot be supposed that he had other means of estimating his latitude than by guess, or that he saw any sea coast beyond the Gulf of California.

The following extract is a fair sample of the first effects of the mania.

A correspondent of the New York Tribune, in California, gives the following fearful account of the effects of the plethora of gold in that province :-" As you would suppose, vice of every kind, and in the most horrible forms, prevails here. The runaway sailors work awhile, and collect a quantity of dust, which they spend with the same recklessness that they do so much silver at home. They pay seven or eight dollars per bottle for liquor, have a 'spree' from which they come out destitute, and then begin again. A great deal of sickness prevails, and as one after another dies, he is thrown aside with the utmost indifference, without even a covering of earth. There has not, as far as I can learn, been any quarrelling among the diggers. There is so much room for all to operate that there seems no necessity for any disturbance. What will be the result of all this I cannot have any idea. I shall improve every opportunity to inform you how I am getting along. I have seen the last man on board an English brig, near me, hoist his chest out alone, and scull to shore, abandoning the craft to her fate, the captain and mates and all the others having gone before."

RECENT IMPORTANT INVENTIONS.

We live in an age remarkable for the efforts which are unceasingly made to apply the discoveries of science to the economic purposes of life. At the present moment four striking instances are claiming the attention of practical

men.

We have the electric light threatening to cast all other kinds of illumination into shadows;-attempts on a large scale are making to employ electro-magnetism as a motive power; we are promised boilers for steamengines which shall be inconceivably small, through the agency of drops of water in, what is called, the spheroidal state;-and by the use of chloroform the expense of motive power is to be reduced to something like a quarter of its present cost, or even less.

The electric light with which M. Archreau some years since illuminated the streets of Paris, and Mr. Staite is dazzling the eyes of the Londoners, is certainly a most brilliant result. Up to the present time this has been produced only by the use of troublesome and costly apparatus; but Mr. Staite assures the public that he has succeeded in completing an arrangement of materials by which the electrical power can be supplied at a cost far beneath any other known method-that his battery will be simple in charging and discharging, and capable of furnishing a current uniform both in quantity and intensity for any required period. As the specification of the patentee is to be made on the 14th of this month, we shall soon have an opportunity of testing the correctness of this assertion. Some interesting researches of M. Mans, of Namur, on the mechanical transference of ponderable matter from the positive to the negative pole, when the electric current is established in a vacuum, appeared to point out other difficulties in the mechanical adjustments, which are not, we think, met by the ingenious arrangements of Messrs. Staite & Petrie.

Since the discovery by Ersted of the magnetic power imparted to bars of iron by an electric current traversing copper wire coiled around them, numerous attempts have been made, with various degrees of success, to move machinery by the enormous force which we have thus at our command. The most remarkable experiments are those of Prof. Jacobi, who, in 1838 and 1839 succeeded in propelling a boat upon the Neva at the rate of four miles an hour. At this time an engine is in process of construction in London, under the direction of Mr. Hjorth, a country-man of the great discoverer of electro-magnetism, which the patentee supposes will give a power equal to five horses. We have seen the model, which certaily embraces many new features that promise to render the application of the power more effective than it has been hitherto. One of the electro-magnets made for the large engine, in a recent trial, supported nearly 5,000 lb., and its attractive force at one-eight of an inch was equal to nearly 1,500 lb. As this force can be multiplied without limits, the question is reduced entirely to one of economy and convenience.

When Dumas discovered chloroform by distilling alcohol from chloride of lime, it was little thought that it would become the valuable therapeutic agent which it has proved to be. Applications run fast in these busy days; and at Messrs. Horne's in Whitechapel, we have an engine working under the combined influence of steam and chloroform,-a combination which the best engineering authorities state to possess many great advan tages. It is not easy to render mechanical details familiar without the aid of diagrams; but the principles of this "combined vapour engine" may be rendered intelligible by a brief general description. The steam having done its work of moving the piston in one cylinder, escapes into another in which is a quantity of chloroform in small flat tubes. This substance volatilizes at a very low temperature; and it thus is converted into vapour of considerable elastic force by the heat of the waste steam-and is in this state employed to work a second piston. We have, indeed, two engines combined in action-one moved by steam-the other by chloroform. The professed advantages are the saving of 50 per cent. in fuel-and as all the steam is rapidly condensed in the same evaporation of the chloroform, the same water is constantly returned to the boiler, by which the necessity for using salt or impure water is avoided. The first engine of this kind was constructed in 1846, in Paris, in which ether was then employed. This engine is still working in a glass manufactory at Lyons-chloroform being substituted. A Parisian paper informs us that M. Charles Beslay has, by order of the Minister of Marine, constructed a very powerful engine of this description, which is pronounced by a commission to be perfectly efficient, A question having been raised as to the effect of chloroform on the health of the sailors, Mr. Quoy, Inspector-General of the medical branch of the marine services, has reported favourably. We learn, however, that the English patentee proposes to use a volatile fluid which is much less expensive than chloroform, equally efficient, and less obnoxious.-Athenæum.

NAUTICAL NOTICES.

H.M.S. Bonetta, Gallinas, August, 1848. SIR.-All the Admiralty charts mark the current between the Sherboro River and Cape Mount, (West Coast of Africa) as turning to the S.E., and

in many of them no current is marked.