Livingstone was not the only man of mark who frequented that room, and got lessons from Mr. Young “how to use his hands.”  The Right Hon. Lyon Playfair, who has had so distinguished a scientific career, was another of its habitues.  A galvanic battery constructed by two young men on a new principle, under Mr. Young’s instructions, became an object of great attraction, and among those who came to see it and its effects were two sons of the Professor of Mathematics in the University.  Although but boys, both were fired at this interview with enthusiasm for electric science.  Both have been for many years Professors in the University of Glasgow.  The elder, Professor James Thomson, is well known for his useful inventions and ingenious papers on many branches of science.  The younger, Sir William Thomson, ranks over the world as prince of electricians, and second to no living man in scientific reputation.

Dr. Graham’s assistant devoted himself to practical chemistry, and made for himself a brilliant name by the purification of petroleum, adapting it for use in private houses, and by the manufacture of paraffin and paraffin-oil.  Few men have made the art to which they devoted themselves more subservient to the use of man than he whom Livingstone first knew as Graham’s assistant, and afterward used to call playfully “Sir Paraffin.”  “I have been obliged to knight him,” he used to say, “to distinguish him from the other Young.”  The “other” Young was Mr. E. D. Young, of the Search Expedition, and subsequently the very successful leader of the Scotch Mission at Lake Nyassa.  The assistant to Dr. Graham still survives, and is well known as Mr. Young, of Kelly, LL.D. and F.R.S.

When Livingstone returned from his first journey his acquaintance with Mr. Young was resumed, and their friendship continued through life.  It is no slight testimony from one who knew him so long and so intimately, that, in his judgment, Livingstone was the best man he ever knew, had more than any other man of true filial trust in God, more of the spirit of Christ, more of integrity, purity, and simplicity of character, and of self-denying love for his fellow-men.  Livingstone named after him a river which he supposed might be one of the sources of the Nile, and used ever to speak with great respect of the chief achievement of Mr. Young’s life,—­filling houses with a clear white light at a fraction of the cost of the smoky article which it displaced.

Beyond their own department, men of science are often as lax and illogical as any; but when scientific training is duly applied, it genders a habit of thorough accuracy, inasmuch as in scientific inquiry the slightest deviation from truth breeds endless mischief.  Other influences had already disposed Livingstone to great exactness of statement, but along with these his scientific training may be held to have contributed to that dread of exaggeration and of all inaccuracy which was so marked a feature of his character through life.