most sensitive of animals. A slight or a disappointment mortifies him deeply. The elephants of South Africa, which are rough animals when compared with those raised in captivity, die from diarrhœa or constipation, as Le Vaillant has stated. Their tamer brethren are free from disease; and, if they die before their time, they generally do so from the above-mentioned causes. Sultan, the pride of the Jardin, the most amiable elephant I ever knew, was unable to survive the death of his companion, the pet dog Jean.
TO throw light on the title of this lecture I must go back more than sixty years—to 1816. Faraday, then a mere student and ardent experimentalist, was twenty-four years old, and at this early period of his career he delivered a series of lectures on the general properties of matter, and one of them bore the remarkable title, "On Radiant Matter." The great philosopher's notes of this lecture are to be found in Dr. Bence Jones's "Life and Letters of Faraday," and I will here quote a passage in which he first employs the expression radiant matter:
Faraday was evidently engrossed with this far-reaching speculation, for three years later—in 1819—we find him bringing fresh evidence and argument to strengthen his startling hypothesis. His notes are now more extended, and they show that in the intervening three years he had thought much and deeply on this higher form of matter. He first points out that matter may be classed into four states—solid, liquid, gaseous, and radiant—these modifications depending upon differences in their several essential properties. He admits that the existence of radiant matter is as yet unproved, and then proceeds, in a series of ingenious analogical arguments, to show the probability of its existence.
- A lecture delivered before the British Association for the Advancement of Science, at Sheffield, Friday, August 22, 1879.
- I may now notice a curious progression in physical properties accompanying changes of form, and which is perhaps sufficient to induce, in the inventive and sanguine philoso-