MR H. A. SEVERN'S SCIENTIFIC LECTURES.

Otago Witness, Issue 1324, 14 April 1877, Page 17

MR H. A. SEVERN'S SCIENTIFIC LECTURES.

Mr H. A. Severn delivered the first of a eeries of " Experimental Science Lectures " in the large hall of the University on the ,6th. The attendance was lange, and the impression created by the lecturer was a most favourable one. He has a very interesting manner of handling his subject, and makes his meaning plain to all. The chair was taken by His Worship the Mayor, .who said that he had much pleasure in occupying the chair on that occasion. Mr Severn commenced his career in New Zealand as a professional lecturer, but for many years past he had given his services on behalf of charities. He (the Mayor) had no doubt but the audience would fully appreciate that fact, and give Mr Severn hearty support. Having referred to the flattering reports which appeared in the northern papers concerning Mr Severn, he concluded by introducing him to the meeting. The Lecturer said that he had never visited a place where he received a larger amount of sympathy and kindness than in Dunedin. He then proceeded to say lhat England owed her present position to her scientific investigations. The readiness with which that building had bean placed at his disposal by the Chancellor was significant, and showed that the people of Dunedin were progressive. Proceeding then to comment on the subject of his lecture, he said that no doubt many cf them had seen the sun rise, but others perhaps had not. He urged upon them to try and believe when they did see the sun rise that it was not the sun which was rising, but that it was they who were moving along with the earth. He proposed to examine the sun telescopically, and spectroscopically. Referring to the heat and light emitted by the sun, he said that the quantity of the former was equal to what would be produced by eleven thousand six hundred millions of millions of tons of coaL If the light of the sun were blotted out, chaos would be the result. He then dwelt at considerable length upon the phenomena of the sun's spots and strongly urged upon his hearers the necessity of cultivating habits of observation, and gave instances of the valuable results which had arisen from such a course being adopted. Mr Severn then proceeded to the practical portion of his lecture, and gave a large number of very interesting experiments illustrative of solar phenomena, and concluded with, others, displaying the power of the microscope. During the delivery of his lecture, he waj frequently applauded, The third lecture of the series was delivered on the 9th, and we were much pleased to see the University flail again crowded. The subject was "Light and Spectrum Analysis,"

Mr Severn had made very considerable preparation, and performed the most difficult experi . ments. « Newton's theory regarding light was first explained. The velocity of light, as discovered by the eclipses of Jupiter's moons, was next exhibited, and explained by means of a beautiful diagram in motion. Young's undulatory theory— reflection, refraction; and then Newton's experiments with the prism were practically carried out by means of Mr Browning's beautiful apparatus thus: A beam of light was projected through a small aperture, and formed an image on the screen ; a block of glass was intercepted, and the beam bent ; then the beam was received on a reflector and phosphorus burnt in the focus; tbe heat was then lifted out of this beam of light by means of a trough containing a chemical solution, and though there seemed to be the same quantity of light as before, it failed to explode the phosphorus, because the heat was now sifted out ; the light was taken oat of the same ray by means of iodine, and yet it burned the phosphorus, because the heat was yet present. A photograph was taken in the violet or invisible light rays of the spectrum, and thrown on the screen, to the^great satisfaction of the audience. Other beautiful experiments followed, such as flowers placed in the spectrum, when the causa of the visibility of colour was made apparent, for a red rose was black in every part*of the spectrum but the red ; it absorbed every other colour, but red it reflected, and thus became visible.i ble. The microscope views and kaleidoscope brought the discourse to a close.