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.
It happened that Livingstone did not part company with Professor Graham and Mr.Young when he left Glasgow.

The same year, Dr.Graham went to London as Professor in University College, and Livingstone, who also went to London, had the opportunity of paying occasional visits to his class.