oxide, or some other carbon compounds, and therefore these stars must be subject to a lower temperature than that of the first two types."

We would arrive at the same conclusion in admitting Lockyer's opinion regarding chemical elements, because in this view compound bodies, when the temperature is raised, are decomposed into their constituent elements, and these, at high temperatures, would all be reduced to hydrogen or to a few elements. In this opinion the stars of the first group, since they are the hottest, are composed mainly of hydrogen. The sun and other stars of the second type are at a temperature at which metals exist, but not their compounds, these latter being found only in the cooler stars.

To conceive some definite idea of the temperature of the stars, let us remark, with Fr. Secchi, that compound bodies, such as calcium oxide, can exist even at the temperature at which platinum. melts, since the lines of this oxide are observed in the lime crucibles employed for the fusion of platinum. Now, in the sun and in some of the stars, calcium exists in the metallic state, consequently the temperature of these bodies is higher than the melting-point of platinum, the most infusible of metals.

We cannot, therefore, help admiring the exactness of Newton's remarks, who, long before science had reached the results which we have indicated, spoke thus in his eleventh query regarding the stars: "Are not the sun and fixed stars great earths, vehemently hot, whose heat is conserved by the greatness of the bodies, and the mutual action and reaction between them, and the light which they emit, and whose parts are kept from fuming away, not only by their fixity, but also by the vast weight and density of the atmospheres incumbent upon them, and very strongly compressing them, and condensing the vapors and exhalations which arise from them?"

To render somewhat complete this brief sketch of what the spectroscope has revealed regarding the condition of the stars, we shall touch upon a few other points alluded to in the beginning. We stated that ordinary methods of observation had shown that many of the so-called fixed stars, perhaps all, have an angular displacement. This, however, does not represent the total stellar motion, for the entire motion can be regarded as twofold; one in the direction of the visual ray, to which the second is perpendicular. This second is given by the displacement above mentioned, not in absolute length, but in an arc of a circle, whose dimensions are unknown, because the distance of the stars is unknown. But spectroscopic observations on the Fraunhofer lines, as explained hitherto, give the true value of the first motion. This method, which Huggins and Secchi first applied to the stars, gives only the relative VOL. IV.-43

velocity of the earth and of the star under examination. But from this we can pass to the relative velocity of the star and of the sun by making the necessary correction for the motion of the earth in its orbit. By this method, which meets with many difficulties in its practical application, Huggins has shown that Sirius and Regulus recede from the sun with a velocity of about twenty miles a second; that Rigel's and Castor's rate is nearly twelve; and that all the stars of the Great Bear, except a, also recede; while, on the other hand, this star and Arcturus approach at the rate of nearly forty miles per second; and Vega, a Cygni, a Pegasi, etc., also approach. Fox Talbot has suggested the application of this method of discovering the velocity of the stars by the shifting of the lines in their spectra to some physical systems of double stars, with the view of determining their distance from us; at least when they have one common absorbing constituent in their atmospheres. If we observe a double star, the plane of whose relative orbit passes through or near the earth, and if by ordinary astronomical obser vations we can determine the points at which the tangents to the orbit of one star revolving around the other are parallel to the visual ray, then measuring the relative velocity of the two stars (which is the actual velocity at which one rotates around the other), we can calculate the dimensions of the orbit described, and having observed the angle subtended by it, we can deduce the distance of the double star from our own planet. The process is exact, but the difficulties to be encountered are appalling.

The spectroscope, furthermore, has solved a problem presented by some double stars, which for a long time somewhat puzzled astronomers. Many double stars when examined with the telescope were found to exhibit complementary colors. It was doubted whether these colors were real or due to an optical illusion. Now, on examining these stars with the spectroscope it was found that in some cases one star presented a spectrum in which there was absorption of one color, while the complementary of that color was absorbed in the spectrum of the second star. In other cases, one star has appeared nearly white, while in the other the blue and green were almost entirely cut off by absorption. Hence these last stars are, the one white, the other red; but by an optical effect of contrast one appears green, the other quite red, while in the first case the complementary color is the real color of the star.

Let us, in conclusion, make a few remarks pertaining to spectroscopic observations on the variable stars, both periodical and temporary. The most remarkable periodically variable star is o Ceti, also called Mira, whose period is 331 days, 8 hours. For about five months it is invisible to the naked eye; then in three months it reaches the brightness of a star of the second magnitude,

and afterwards gradually disappears. Examined by the spectroscope at its maximum brightness it is yellow, and can be classed among the stars of the third type; during its decline it becomes reddish, and preserves only a few very fine and quite faint lines. Two temporary stars have been discovered since the invention of the spectroscope, one in 1866 in the constellation of Corona Borealis, the other in 1876 in Cygnus.

Before the application of the spectroscope to the stars, they were examined simply to note their change in luminous intensity and color, only vague hypotheses being advanced to account for the variations. The spectroscope enables us to distinguish three classes. In some the variations, which are generally of short duration, are caused by the periodical occultation of opaque bodies; thus Algol, which appears very bright for two days, diminishes in intensity to the minimum in three hours, and, remaining at this point for seven or eight minutes, it again brightens up in three hours. Now during all these changes its spectrum varies only in intensity, remaining unchanged in character. Hence the variation seems to be due to meteoric clouds, which move with a uniform motion, and when interposed between us and the star diminish its intensity. In others, again, the variation arises either from the rotation of the star itself, thus presenting different sides differently illuminated, or from a periodical emission of interior vapors, which produce a phenomenon similar to the solar spots. From unknown causes, referred by many to electricity, the sun's activity is variable. The interior eruptions of vapors, which are seen under the form of protuberances, and which produce by their absorption the solar spots, reach a maximum every eleven and a half years. Now as the phenomena remarked in some temporary stars, Mira for instance, are similar to the solar spots, only more marked, they are attributed to a like cause. In the third class the periods are irregular and unknown, the variation being due to immense fires, whose cause is unaccounted for, though attributed by some to the shock of planets or comets impinging upon them. The spectroscope, in fact, discovers bright lines in the spectra of some temporary variable stars, which are indicative of sudden and extensive conflagrations. Huggins has found the temporary star discovered in 1866 to contain mostly burning hydrogen; while in that discovered in 1878 Cornu found magnesium, sodium, or helium.

The foregoing sketch of the work accomplished by the spectroscope, though quite incomplete, comprises the main points which it has revealed regarding the stars; we say regarding the stars, for it has made known many other facts more or less connected with the present subject, which brevity obliges us to omit. Thus it has rendered more evident that the scintillation of the stars is

a phenomenon of terrestrial origin, depending on the motion of our atmosphere. It has shown that some of the nebulæ, contrary to previous opinions, cannot be resolved into separate stars, as has been done for many; for their spectra having bright lines are indicative of glowing gases. It has revealed various new facts pertaining to comets, meteorites, etc. So that glancing back over what has been achieved by this small instrument, we are simply astounded at the progress made; and this progress will doubtless open up facts hitherto hidden, not only in stellar physics, but in other branches of science.

MY

THE MORMONS.

Y rambles in the Rocky Mountains commenced in the year 1860, when, after a trip of about two months and a half across the plains, I was stationed at Camp Floyd, Utah, and there made my first acquaintance with Mormonism. The post was the one established by General A. S. Johnson when he entered the Territory in 1858, and was situated about forty-five miles south of Great Salt Lake City, in a flat sage-bush plain, with very few Mormon settlers in the immediate vicinity. Numbers of them, however, used to come to the post with vegetables and other articles. to sell, and in an emergency once I had occasion to employ as a nurse in my family a Mrs. W., a most estimable woman, wife, and mother, whose excellent qualities and kind services will long be remembered. Of course the "peculiar institution" of the Mormon people was frequently touched upon in conversation, and it was remarkable with what tenacity the doctrine of polygamy was defended, and sometimes by even the women themselves. This, however, is not by any means universal, and good Mrs. W. did not hesitate to express herself against the doctrine, at the same time that she entertained the fear that W. (her husband) might be "counselled" to give another "mother" to her children, in which event she did not know what he would do. With the men I frequently discoursed, interlarding bargains for potatoes and turnips with theological discussions, and the price of vegetables was not unfrequently intermingled with the price of sins in the next world, quotations from Scripture, and the "prophecies" of Joe Smith. Many of them exhibited considerable knowledge of the Bible, and one honest fellow did not hesitate to quote it as authority for

the modern practice of polygamy, saying that the patriarchs of old, "the chosen of the Lord," were notoriously polygamists, and that the modern people of the Lord (the Latter Day Saints) were but doing what had been plainly sanctioned by the Almighty. It was in vain to plead a less barbarous age and a later dispensation. The Mormon disputant rather demurred to the idea of any advance in civilization, and claimed a later revelation still through Joseph Smith and Brigham Young. As they always implicitly relied upon this latest revelation to the "Lord's chosen people," I soon found that as no premises could be agreed upon the resultant logic did not amount to much, and all argument ended, as it but too frequently does on such subjects, by leaving the disputants more firmly fixed than ever in their original convictions.

But we were soon called upon to enter into transactions more important than the discussion of theological questions, or the status of the Latter Day Saints; for the news reached us by "pony express" of the fall of Fort Sumter and the commencement of the civil war. We waited with impatience for the arrival. of the order recalling our garrison to the East to participate in the defence of an imperilled country. The long-expected and anxiously anticipated order did not reach us till late in the spring, having gone by mistake to California, and it was not until the 27th of July that the troops moved out in a long dusty column from the partially dismantled post on their twelve hundred miles march to the eastward. A large quantity of stores of all kinds had been accumulated at the post, and it became a matter of some importance to determine what disposition should be made of them, for many of the stores consisted of arms and ammunition, and as nearly all the public transportation had been sold by orders from the late Secretary (Floyd) these could not be transported East. To send them by contract freight would cost more than they were worth, even were there any certainty that they would reach their destination. The policy of permitting them to fall into the hands of the Mormons was questionable; for they had been brought into the country by an army sent to compel these people to acknowledge the authority of the Government, and now that the Government was threatened with a more formidable rebellion there was no attempt on the part of the Mormons to conceal their satisfaction, and no lack of "prophecies" on the part of their leaders, that the day of Mormon vengeance was come, and the doom of the unjust Government of the United States sounded. To turn these military supplies over to them therefore was to place arms in the hands of probable enemies. It was, therefore, decided to destroy the arms and ammunition, and hundreds of excellent rifles and millions of cartridges were ruthlessly committed to the