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Jaid in ruins; the city of Conception was three times demolished in the course of fifty years; and once the Spaniards were on the point of abandoning the whole country in despair. Such is the energy of a people determined αλφα.

to be free.

EXTRACTS ON CALORIC.

The meaning of the word heat is so well understood, that any attempt to define it is unnecessary. When we say that a person feels heat, that a stone is hot, the expres sions are understood readily. Yet in each of these proposititions, the word heat has a distinct meaning. In the first it signifies the sensation of heat; in the second, the cause of that sensation. To avoid the supposed ambiguity of these two meanings to one word, the term calorie was invented to signity the cause of heat. When I put my hand on a hot stone, I experience a certain sensation, which I call the sensation of heat; the cause of this sensation is caloric.

Two opinions respecting the nature of caloric have divided philosophers. According to some, like gravity, it is merely a property of matter, while others consider it as a peculiar substance. The latter opinion was first broached by the chemists, and is at present acceded to by almost the whole body of philosophers. A recent discovery of Dr. Herschel has rendered this opinion, if possible, still more plausible than before.

Dr. Herschel, while employed in examining the sun by means of telescopes, thought of examining the heating power of the different rays separated by the prism. He found that the most refrangible rays have the least heat. ing power, and that the heating power gradually increas es as the refrangibility diminishes. The violet ray of course has the least, and the red ray the greatest heating power. It struck Dr. Herschel as remarkable, that the illuminating power and heating power follow different laws. The illuminating power is greatest in the middle of the spectrum, but the heating power is greatest at the red end. This led him to suspect, that the heating power does not stop at the end of the spectrum. On trying the experi

ment, he found that a thermometer placed a little beyond the spectrum rose still higher than when in the red ray. This important experiment was succesfully repeated by Sir Henry Englefeld. Hence it follows, that there are rays emitted from the sun which produce heat, but have not the power of illuminating: consequently caloric is emitted from the sun in rays, and the rays of caloric are not the same with the rays of light.

All the illuminating rays have the power of exciting heat. It is probable that they derive this power from rays of caloric mixed with them; for the rays from the moon, though they consist of the seven prismatic rays, do not, even when concentrated, affect the most delicate thermometer.

The rays of caloric are refracted and reflected preeisely as the rays of light. They obviously move with a very considerable velocity, though what that velocity is we do not at present know It has been ascertained that calorie produces no sensible effect upon the weight of bodies; the weight remaining sensibly the same, whether a substance be hot or cold. In this respect it agrees with light. It agrees with light also in another property, its particles are never found cohering together in masses.

Every addition or abstraction of heat produces a corresponding change in the bulk of the body affected. In general, the addition of heat produces expansion, and the abstraction of it produces a diminution of bulk. To this general law there are perhaps one or two exceptious.

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The property which bodies have of expanding when heat is applied to them, has suggested an instrument for measuring the relative temperatures of bodies. This instrument is the thermometer. A thermometer is a hollow tube of glass hermetically sealed, and blown at one end into a hollow globe or bulb. The bulb and part of the tube are filled with mercury. When the bulb is plunged into a hot body, the mercury expands, and of course rises in the tube; when it is plunged into a cold body, the mereury contracts, and of consequence sinks in the tube. Thermometers are made in this way. The requisite quan-tity of mercury being introduced, the thermometer is plun- ged into melting snow, and the place where the mercury stands is marked. This is called the freezing point. The thermometer is then plunged into boiling water, and the

point at which the mercury stands marked. This is ealled the boiling water point. The distance between these

continued indefinitely above

two points is divided into a number of equal parts called degrees, and these degrees are and below these two points.

BIBLE CLASS IN ROXBURY.

TO THE EDITOR OF THE MONITOR

Dear Sir,-As the principal object of your useful Publication is the benefit of the young, I hope the following will not be uninteresting to your youthful readers, and is at your option, to be used as you please.

I Have noticed with interest and pain, that those pea. ple, who are the most fond of doctrines, commonly term. ed liberal, devote little time or pains to the study of the holy Bible. But few of them are found among the friends of Bible Societies, Sabbath Schools, or any other associ ations, whose object is the religions instruction of the young and ignorant. On the other hand, it has afforded me much pleasure to see the varied and unremitting exertions, which have of late been made, by all the friends of evangelical piety, to render efficient, systematic, and purely scriptural, the means of religious knowledge, es pecially among the young.

Bible Classes, promising great good to Zion, are a new era in the Church. The oue under my care was cobstituted in May last, and is composed of young persons from thirteen years old and upwards. Our number, as yet is small, consisting of about forty members only. I meet them once in two weeks, at four o'clock in the afternoon. We were constituted under the eye of the author of the Bible Class Text Book, which is used by the Class. His presence has given a lively interest to the meeting whenever he has had the goodness to call upon us. have recently added the reading of the Reference Testament, with a critical application of the Key. Before obtaining the Testament, I used to open the exercises of

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the Class by reading and expounding a portion of sacred Scripture, followed by prayer. But I find, by giving each member of the Class an opportunity to take a part in the exercises, a deeper interest is exeited. After prayer, I proceed to hear the answers which they have committed in the Bible Class Text Book, beginning with the youngest division, and interspersing such questions and remarks as may be calculated to fix the subject on the conscience and touch the heart of the pupil. After the close of these recitations, a short address is made, illustrating the importance of a knowledge of Divine things in early life, together with their dependance on the teachings of the Holy Spirit to render their biblical knowledge saving. We then read such pieces as have been composed by the members on Divine subjects, and close with prayer.

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I attend no meeting which yields me more pleasure than the one I have described. Some of the members of the Bible Class are also members of the Church; others are very seriously inelined, and all have precious souls, which, if sanctified at all, must be sanctified through the truth of the Divine word. Their improvement has far exceeded my highest expectations. My labour has not been in vain, neither have I spent my strength for nought." A faithful Pastor, with the aid of the books which I have named, may render the young of his flock familiar with the leading truths of the Bible, and thus guard them against the popular errors and vices of the day, and, by the blessing of God, save their souls. I greatly rejoice to see so much doing on this subject. At a late annual meeting of the Boston Baptist Association, it was recommended to the Pastors and Churches composing that body, to give particular attention to catachetical and Bible Class instruction among the young connected with them in the worship of God. These measures were ably advocated in on address from a beloved brother of the association. I believe that Bible Classes are now in operation in most of the orthodox Churches in Boston and its vicinity. Would to God they were as numerous as the ministers of Christ, and they multiplied till all the earth were filled with the knowl edge of God our Saviour.

Should the above be acceptable, you may expect to hear again from the Instructor of the Bible Class in Roxbury. JOSEPH ELLIOT,

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A WORD TO SUNDAY SCHOOL TEACHERS.

MR, EDITOR, Most of those who read your useful publication, feel deeply interested in the prosperity of Sunday schools. A Sunday school teacher has lately adopted the following plan, to gain the attention and af fections of his scholars. His class consists of ten females, who are about twelve or thirteen years old. At the first meeting, he promised to lend them, weekly, some entertaining and instructive pamphlet, so long as the school continued, on the condition that they should continue to perform, in a manner satisfactory, the duties enjoined on them. He had received the six first numbers of the Monitor. To these he added four new tracts; and the next Sabbath, lent them to his scholars. The effect was good. Joy sparkled in the faces of these amiable youth. At their next meeting, the teacher was exceedingly grat-ified with their correct deportment, and rapid progress in scripture knowledge. He directed them to exchange with each other weekly, what he had lent them, so that every scholar would have a new pamphlet to read. By this means, they would all enjoy the privilege of reading each of the books; should the school continue ten weeks. This direction has for some time been observed: and the result fully answers the expectation of the teacher.

A FRIEND TO CHILDREN.

FOR THE MONITOR.

OBITUARY NOTICE..

DIED in Dorchester, Sept. 22, 1823, Miss FANNY TILESTON CLAP, daughter of Deacon Joseph Clap, in the 20th year of her age.

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In her character, religion shone with no common lusBlessed from her infancy with a religious education, and enjoying in a high degree the advantages of

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