MR. SEVERN'S LECTURE.

Thames Star, Volume VII, Issue 2026, 2 July 1875, Page 2

MR. SEVERN'S LECTURE.

Mr H. A. Severn delivered the last of Ms series of lectures yesterday evening, and, notwithstanding the unpropitious state of; the weather, had a very good attendance. The lecture was illustrated by the usual experiments, with additions of a most interesting character. Nearly everything handled by ■Mr Severn was successful,, and explained with. as much clearness as the nature of the subjects, for there were many, would admit. He commenced by briefly glancing at the former lectures, as an introduction to the present, and explained the electric light and spectrurni and-the-difficulty there was in the .experiments which he was about to make. In doing this he explained galvanism* and the nature and working of the 50-cell battery (which, we may add, en passant, was entirely constructed by Mr Severn at considerable' expense). With regard to the electric light, he informed his hearers that the great desideratum sought after by scientists was a steadfast light, without whiclr due effect could not be given to the experiments. This object was obtained in, the .lamp invented, by Mr Browning, his (Mr Severn's) being by that maker. The matter of difficulty was to show iipon the canvas the spectrum of the metal fusing in the lamp instead of the spectrum of electric light; After mating some remarks upon the use of spectrum analysis in. connection with the working of iron, the lecturer passed on to the practical illustration of his subI'eot, and produced some new and unquestionably interesting effects. He first showed a number of views which were exhibited by means of the oxy-hydrogen light as on the two former occasions. The 50-cell battery was then prepared, and by the aid of the powerful electric light he exhibited the decomposition 'of water on the screen. This was the most beautiful experiment of the evening. Two pieces of glass placed sufficiently close together to hold a sheet of water were fixed in a frame, and, being filled, were placed in the lamp, and the electricity being applied to the connecting , wires in the glass, the action of decomposition was exhibited on the screen with beautiful results. Mr Severn next took a photograph of an illustration in Punch, with equal success, and displayed a reflection of the negative on the screen. Following this was the exhibition of animalcula) ia waier, .which - caused, some amusement. The life that is known to exist in water was magnified so that some of the animalcule appeared as large as small rats, and a tadpole, or mosquito, was shown. The fulhnoon, the planet Jupiter, blood, milk, and live fleas, were also shown on tlie screen, aud caused no little wonderment. We. that Mr Severn will deliver auother lecture in the course of a few weeks, on " Modern, astronomical discoveries,"