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DEAR SIR,

Since I saw you, I have made only one experiment on magnetism. I determined the power of my magnet, as it had been shut up in the dark for a long time, and lying down. I then exposed it to the rays of the sun, also lying down, and remote from the iron support, and I found that it had gained 12 oz. power in 40 minutes, and 14 oz. power only in five hours.

From the Annals of Philosophy for March, 1818. Communicated by Mr. THOMAS GILL.

This lamp is one of the results of the new discoveries in chemistry. It has been found, by Sir H. Davy, that a fine platina wire, heated red hot, and held in the vapour of ether, would continue ignited for some time; but, I believe, no practical use has been made of this fact.

The proper size of the platina wire is the 1/100th part of an inch: a larger one will only yield a dull, red light, and a smaller one is difficult to use. About 12 turns of the wire will be sufficient, coiled around any cylindrical body suited to the size of the wick of the lamp; and four or five coils should be placed on the wick, and the remainder of the wire above it; and which will be the part ignited. A wick, composed of twelve threads of the ordinary sized lamp cotton yarn, with the platina wire coiled around it, will require about half an ounce of alcohol to keep it alight for eight hours.

An agreeable and slightly acid smell arises from this lamp during its ignition. It is perfectly safe, as nothing can fall from it; and its novel appearance, in a wick's keeping red hot for such a length of time, is very surprising to persons unacquainted with its nature.

P.S.--When the wire has become oxided, it will be necessary to uncoil it, and rub it bright again with fine glass-paper; which will cause it to act again with increased effect.

REMARK.

Such wire as is here described may, probably, be obtained in Philadelphia.

FOOTNOTES:

In using the word "pit," instead of "mine," I have accommodated my language to the custom of the country.

Since the above article was written we have received some as large as a finger.

The green earth of most mineralogists. EDITOR.

Doubtless the pea ore of the Wernerians. EDITOR.

This jet of cold water being let into the cylinder itself, necessarily cooled it at every stroke; and then it was necessary to heat it again to the boiling point, before the piston would reascend, and thus a vast loss of heat occurred. EDITOR.

Taken from the Philosophical Magazine, and by that work from the Annales de Chimie and de Physique, for January, 1818.

A method of rendering changeable the sound of the same pipes in the organ, which had occurred to the writer, but which was not inserted above on account of the supposed difficulty of making the change sufficient in degree, he has since found to have been executed by the Rev. H. Liston, who has succeeded, by means of shaders capable of being brought before the mouths of his pipes by the action of pedals, in giving them three distinct sounds each, varying by two commas. His scale embraces 59 intervals to the octave, and is intended to produce perfect harmony in all the keys. But as it will require the use of pedals perpetually, even on the same key, and a ready and perfect knowledge of small musical intervals, which practical musicians can seldom possess, there is no probability that it will ever be extensively adopted. Perhaps, however, four or five sounds, such as D?, E?, A?, D?, might be added to the common scale of 12 intervals by means of his mechanism, with advantage. An instrument thus furnished would require the use of pedals but seldom, and would contain chromatic degrees sufficient for the accurate performance of the great mass of organ music.

These picture, as is well known, represent the assault on Quebec, and the battle of Bunker's Hill.

GEOLOGY, MINERALOGY, TOPOGRAPHY, &C. Page

Limpid Quartz in West Canada Creek, N. Y. 241

BOTANY.

ZOOLOGY.

PHYSICS AND CHEMISTRY.

AGRICULTURE AND ECONOMICS.

MISCELLANEOUS.

INTELLIGENCE.

THE

JOURNAL OF SCIENCE, &c.

INTRODUCTORY REMARKS.

Some years since, during Mr. Maclure's geological survey of the United States, the editor had the pleasure of passing a few days, in company with that gentleman, in exploring the geology of the vicinity of New-Haven. Near that town, junctions, on an extensive scale, between widely different formations, are to be observed. A radius of ten miles, with New-Haven for a centre, will describe a circle within which the geological student may find most of the important rocks of the globe, and a radius of even six or seven miles will include the greater number of these. At, and near the terminations of the primitive ranges, there are rocks which appear to have, in a high degree, the characters of the transition class. Among them is the beautiful green marble of the Milford Hills, seven miles from New-Haven. Mr. Maclure visited that district, and even suggested the first hint which afterward led to the discovery of the marble. Doubts being entertained concerning some of the geological relations of those rocks, a letter was addressed to Mr. Maclure on the subject. His answer is subjoined.

In giving it to the public, the editor takes a liberty which he hopes the respectable author will pardon, because his production, although evidently never intended for the public eye, contains statements and opinions of no small importance to the young geologist, especially of this country.

With these explanatory remarks, the following extract of Mr. Maclure's letter is now subjoined:

DEAR SIR,

Your letter of the 26th June came just as I was embarking for Europe. The information it requires concerning the primitive trap and flint slate, the transition and secondary rocks, &c. &c. is difficult to give without the aid of specimens, and frequently requires the examination of the relative position of the strata before any correct idea can be formed. I will, however, endeavour to give you the little my experience has brought me acquainted with.

Following the nomenclature of Werner, I have given a list of his rocks; but in describing them there are many of his names which I do not use; because I never met with them. Primitive trap is one instance--I do not use trap as a substantive, except in describing that kind of trap which Werner calls the newest flaetz trap, the nearest to which is your trap, which covers the oldest red sandstone.

The primitive flint slate is in the same predicament. I have always found it on the borders of the transition, between it and the secondary.

Primitive gypsum I have not found.

What Werner calls primitive trap may perhaps be compact hornblende, or perhaps the newest flaetz trap, when it happens to cover the primitive; for, this species of trap, like the currents of lava, covers indiscriminately all classes of rocks, and is one reason why I consider it as the remains of ancient lava.

Transition trap is a rock that I have not met with, and may perhaps be a part of the flaetz trap that happened to cover the transition, without any immediate connexion, but like a current of lava, overlying all the classes of rocks it meets with. This misapplication of names naturally arises from the system of neptunian origin, on which the nomenclature of Werner is founded.

Greywake and greywake slate are aggregates of rounded particles of rocks, evidently the detritus of more ancient formations, and differ from the aggregates of pudding and sandstone of the secondary class, in the following properties, viz.

The aggregates of transition are harder and much more compact, than the secondary; they are also cemented by argil, taking a slaty form.

This cement is in much greater quantity, in proportion to the particles cemented, and has the appearance as if the cement at the time of formation, had a consistence sufficient to prevent the particles from touching each other.

They have, in common with all the transition rocks, a regular and uniform dip from the horizon, from 10 to 40 degrees; and sometimes more. This is perhaps the strongest mark of distinction which separates them from the secondary, which are horizontal, or follow the inequalities of the surface on which they were deposited.

The transition are distinguished from the primitive in being aggregates of rounded particles, having little or no crystallization, and containing, or alternating with strata, which contain organic matter.

The oldest red sandstone, with all its accompanying strata, I should incline to put into the transition, as having many of the properties of that class, and occupying the same relative situation in the stratification of the globe. It is at a constant dip from the horizon; the cement is in greater quantities in proportion to the particles cemented than in any of the secondary aggregates, &c. &c.

The character of the secondary is a horizontal position, that perhaps does not admit of the same facility of examining the relative situation of its stratification. The compact limestone is, probably, with reason, considered as the lowest of the secondary formation, and always under the coal formation, but it appears to me that the secondary is deposited in basins alongside of one another, and that each basin has a different order of superposition, according to the nature of the agents employed in the deposition; that it is a partial, and by no means a general deposition. The secondary aggregates of sandstone and puddings have been evidently beds of sand or gravel, and of course, in that state would be called alluvial, but when cemented together by the infiltration of water, carrying along with it lime, iron, or any other body capable of agglutinating the particles together, become rocks, and may alternate in all proportions.

I am therefore inclined to think, that in geology the best mode for the greatest part of the secondary would be to give the relative position of the strata of each valley or basin; and I am rather of opinion that they would all differ from one another.

The French and English basin having chalk for the lowest stratum, which has occupied the geologists of both countries for these 10 or 15 years, is perhaps the best known; yet they do not know the relative position of the chalk and coals, because coals have not been found in the same basin with chalk: coals occupy basins filled with different kinds of rocks, and have no resemblance to the rocks found covering the chalk.

SIR,

Having recently returned from a tour of considerable extent in the United States, I avail myself with pleasure of the first leisure moment, to communicate, agreeably to your request, some facts, relative to the Mineralogy and Geology of that part of the country through which I passed.

INTRODUCTORY REMARKS.

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