MR PROCTOR’S LECTURE.

Globe, Volume XXII, Issue 2085, 29 October 1880, Page 3

MR PROCTOR’S LECTURE.

Last night Mr Prootor delivered the third of his series of lectures, the Hall being crowded to excess. The subject chosen was “The Sun.” Mr Prootor, on coming forward, was heartily cheered. He said that in the first place he would answer the questions put to him through the papers. First,as regarded the rarity of the atmosphere of the moon, which belonged in some degree to his subject that night. Mr Prootor then proceeded to speak of the letters which had appeared in the papers respecting the snow on the hills of the moon. The atmosphere, he explained, was so thin that tho sun’s rays passed through it and went off again. The snow was dne to the vapours arising from the valleys and deposited on the mountains of the moon. The whole of the experience of means as regards snow was, that whilst struggling through snow tho heat was exceedingly great. All that the. sun’s rays could do was to melt the snow, hut they were unable during the few hours of sunlight to melt the vast masses of snow deposited night after night. A calculation had been made that if tho sun’s rays were poured vertically upon the surface of a square mile, 26,000 tons of ioe, or two-fifths of an inch in the course of an hour would be dissolved. In a day, provided that the sun’s rays were not in any way obstructed, something like three inches of snow would be melted. Again, supposing this to be so, and the water pouring down, this would also melt some of the snow, the vapour would again go into the clouds and be redeposited in the shape of snow. It was a well known faot that if exposed to the sun’s rays, though ice and snow were around, the atmosphere would be heated. He was also asked how it was the moon could reflect the rays of the sun when she bad no atmosphere. Now, ho oould not answer that question until he understood what part the atmosphere played in the matter. The heat that came from the moon bad been measured, and proved that when the moon was full it was 500 degrees Fah., beyond what it was when it was new. Mr Prootor then proceeded to treat on the subject of his leoture —“ The Sun.” They had become well aware of the constitution of this noble orb, and this had proved that it was the grandest study of the astronomer. First, Mr Proctor considered the force and energy of the sun, which gave life and light and heat to all tho other planets. It was also a benevolent planet, dealing out the bounty of tho Creator as his almoner. Mr Proctor then went on to speak of the size of the sun and the difficulty of comparison of observations, as the sun was constantly rotating, but still it was by observations made under these unfavorable conditions that the distance of 91,000,000 miles was arrived at. Beferenec was made to the time necessary to reach the sun from the earth by, as it were, locomotive power and by a shot fired from an Armstrong gun, and also some fanciful speculations indulged in, particularly that of an American Professor, who made out that if a child were born with an arm ninety-two millions of miles long, and was to reach to tho sun, he would Jflve to be one hundred and thirty-two years old before ho came to be aware that on the first day of his life he had burned the tip of his finger. The period occupied by light in reaching tho earth was next dilated upon, and the well-known theory of the time occupied by the rays of the sun in reaching the earth enlarged upon and expounded by Mr Prootor. Newton’s remarks in the “ Prinoipia ” (on this subject were also noted, particularly the mystery of the law of gravitation. The diameter of the sun, the volume of the same, were then spoken of, and also the might of the central orb, acquired as it was by the size of it. This mass conferred upon the sun the power which it exercised over the other planets, keeping them at such a distance as would enable them to receive the necessary heat, &o. This power was explained by a comparison with regard to an ounce weight, which, if raised one inch, would, assuming the earth to have the power of the sun, be thrown against the earth with a power and weight equal to five tons. The brilliancy of tbe light of the sun was tbe next point tonobed upon by Mr Proctor, and a comparison instituted between tbe power of the electric light and the sun, the latter giving oat millions of times more light than the electric light. The heat of the eun came next under review, and it was calculated that one hundred and seventeen millions of millions of tons of coal would have to be burned to give the same amount of heat as the sun gave out in one second of time. Mr Prootor then proceeded to consider the time it was computed the sun had been at work on the surface of the earth, and Sir William Thompson had estimated this at twenty millions of years, supposing that he had|gathered up all the heat generated by his rays. Other eminent scientists calculated that the sun had been emitting the same amount of heat over one hundred millions of years. The theory they were forced to was that the sun was not so largo as it appeared to be, which _ had been confirmed by a piece of evidence obtained by Mr Charles Darwin, a son of the eminent man of that name, who had devoted himself to working out the shapes of Jupiter, Mars, and the Sun, His observations proved that there was no flattening of the sides of the sun, which Darwin took to be that there was a compression of the body of tho sun in the centre. He (Mr Proctor) thought they might start with this faot, that the sun’s disc was really much smaller than what they apparently saw. Pictures were then shown of the relative size of the sun and of earth, the relative sizes being three inches the size of tho earth and three yards that of the eun. Mr Prootor then proceeded to exhibit and comment on tho photographs of the sun’s disc as shown by the telescope, and the relative sizes of the sun and the other members of the planetary family over which ho ruled. Tho rotation of the eun was next spoken of as shown by the spots, and tho different rates near or removed from the equator touched upon. This oould only be explained by the fact which they had been led to, viz., that tho spots were not on the real surface of the sun, but that it was some distance below them. A photograph of one of the spots of the sun was next exhibited, and comment passed upon the great improvement in photography, as applied to astronomical science. An enlarged photograph of the sun’s surface, as shown by the Harvard telescope, was exhibited. This showed tho spots to be depressions at a lower level than the other parts of the sun’s surface. It seemed to him that the sun was filled with clouds, dropping showers, not of water, but of molten metal, and the spots were, he thought, the result of some mighty storm sweeping away the clouds. In proof of this theory, a sketch of a spot by Father Secohi, taken on the sth May, 1857, was exhibited, showing the action of a fierce whirlwind or tornado. Tho absence of uniformity in spote on the sun was next commented upon, and reference made to Schwabo’s theory of the appearance and disappearance of the spots on the sun. A sketch by Dr. Huggins of the surfaoa of the sun without any spots, and showing what is technically called tho rice grains, was shown. Next to this was a beautiful picture by Professor Langley, of Pittsburgh, snowing the cloud-like masses driven aa it were round tho spots. Reference was made to this picture to bear out the theory that tho atmospheric changes in the sun were going on in a similar manner to those going on heie,but Mr Proctor expressed j his dissent with this theory. A detailed photograph taken by the telescope was next

[exhibited, showing the mottled-like appearance of the sun's snrface ; a photograph of the sun being taken in the sixteenhundredth part of a second. Wheatstone’s measurement of a millionth part of a second was referred to by Mr Proctor. This was applied by Wheatstone to the measurement of a flash of lightning, which was ascertained to be within the millionth part of a second. The constituent parts of the su", as ascertained by the spectroscope, were next described, the pictures exhibited of the results being exceedingly interesting. Mr Proctor proceeded to state that all the colors of the rainbow were to be seen : n the sun, but there were numbers of tints abtsnt, but the discoveries by the spectroscope bro ight them to this conclusion, viz., that hydrogen, iron in vapour, sodium, copper, and aluminium were constituent parts of the sun. Mr Proctor then proceeded to treat of the corona or flame-like appearance outside the sun. Several pictures giving the result of the observations of Zollner were exhibited. In these the prominences were shown to be jets or clondlike appearances, which Mr Proctor said were undoubtedly either solid or liquid matter thrown out from the surface of the sun by a kind of eruption. These jets spread out at the top when they reached their greatest altitude, and he was decidedly of opinion that all the evidence was in favor of their being thrown ont in a violent way. In 1870 Professor Young first observed a tree-like formation, which afterwards assumed the shape of a large column or jet. This supported the theory that these prominences were, as ha had said, thrown out by some eruptive force from the centre of the system of the sun. The zodiacal light which they saw, was the reflection of these jots, like the reflected light which followed a meteor, and the matter thus ejected never returned to the sun, because the velocity with which it travelled was far too great for the sun’s force to exercise any control over it. Thus this matter would continue going through inter-stellar space for millions of years. The meteoric showers would thus come to them from some of the other planets, bringing with them hydrogen, &s., from the fixed stars. Professor Sorby, of Sheffield, had met with these in meteorites. The appearance of the corona of the sun was exhibited in two pictures taken during the eclipses of 18701871, and 1878, showing bands, streaks, streamers, &0., on the corona. The tongues of light projecting on either side of the sun’s disk were next described, and Mr Proctor went on to explain that the working sun was very much smaller than the apparent sun seen by us, being a compressed globe inside the visible body of the orb. Mr Proctor then, in conclusion, spoke briefly of the knowledge on various points connected with the sun which had been gained. It seemed to them that the rays of the sun were wasted, as it was calculated that two hundred and twenty-five millions of rays were emitted to no purpose. But then there was this that they bad learned, that there was an adaptation of the rays, so that each performed its particular function. Mr Proctor concluded a very interesting lecture by reciting a sonnet on the effect produced upon our first parents by the gradual approach of the darkness on the first night in Eden. His peroration was loudly applauded. To-night the last lecture of the course, “The Star Depths,” will be given.