In a work which has more than one author, it is right to distinguish as far as possible what has been contributed by each.

The first part of this book, then, has been mainly composed by the present writer (who has acted as editor), and the second by Mr. Garnett; but it is due to Mr. Garnett to add that, while he had the chief share of the labour of collecting materials for the whole biography, and the entire burden of the account here given of Maxwell's contributions to science, the substance of Chapters XI. XII. XIII. is also largely drawn from information obtained through him. The matter of whole pages remains almost in his very words, although for the sake of uniformity and simplicity the first person has still been used in speaking of my own reminiscences.

The narrative of Maxwell's early life has been facilitated—(1) by a diary kept by Maxwell's father from 1841 to 1847, and often referred to in these pages as “the Diary;” (2) by two albums containing a series of water-colour drawings by Maxwell's first cousin, Mrs. Hugh Blackburn (née Isabella Wedderburn), the value of which may be inferred from the outlined reproductions of a few of them prepared by Mrs. Blackburn herself as illustrations for this book. They are literally bits out of the past, each containing an exact representation, by a most accurate observer and clever draughtswoman, of some incident which had just happened when the sketch was made.