The worthies of Cumberland

without deriving advantage, and here I beg gratefully to acknowledge my indebtedness to them both. They wrote for the scientific public; my effort is a much humbler one, aiming more or less to satisfy the wants of a quasi-popular or less instructed class of readers. The science that Dalton taught has not, however, been lightly passed over in the following pages, but rather epitomised and offered, as far as circumstances permit, in a form comprehensive to all persons of average intelligence.

Favoured by a number of letters of Dalton's, and much original information hitherto unpublished, I am enabled to present my readers with a more correct personal history of the famous chemical philosopher than has yet appeared in print.

Among those with whom I had repeated conversations on Dalton's history may be mentioned my late worthy friends Jonathan and Jane Carr of Carlisle, who were pupils of the Daltons at Kendal, and had a lively recollection of the junior schoolmaster; my charming and joyous-hearted friend Mary Sutton, who thoroughly appreciated the chemical philosopher; and the estimable Mr John Wilson Fletcher of Tarn Bank, near Cockermouth, with whom Dalton invariably spent an evening on all his visits to Cumberland. Many more, especially members of the Society of

Friends, who aided me, have passed the bourne that allows of no grateful recognition. Others, happily, live, to whom I can offer my cordial thanks-namely, my constant friends Isaac Fletcher, M.P., F.R.S., and William Fletcher, Esq. of Brigham Hill, for valuable documents; Henry A. Fletcher, Esq. of Lowca Works; Wm. B. Clarke, Esq. of Barwickstead; and Edward Waugh, Esq. of Cockermouth, for aiding me in my inquiries: to my dear friend Mrs Henry Wigham of Dublin I am indebted for Dalton's correspondence with Elihu Robinson; whilst the letters that passed between Dalton and Joseph Dickinson on colour-blindness came from the valuable repertory of Cumbrian literature of my friend Mr William Jackson of Fleatham House, St Bees.

I was greatly helped in my inquiries at Manchester by my esteemed friend Professor Roscoe, and to Mr G. S. Woolley I am indebted for a perusal of his father's essay, and Dalton's correspondence with the Johns family.

In looking over the history of the Atomic Theory and the opinions of authors, among whom Professor Daubeny stands foremost, I cannot help recalling the eloquent mode in which my Edinburgh associate, and truly a man of genius, Dr Samuel Brown, treated this subject in a series of lectures, which were, after his

death, published in two 8vo volumes by Thomas Constable & Co., under the title "Lectures on the Atomic Theory, and Essays Scientific and Literary, by Samuel Brown."

The portrait of Dalton in the frontispiece, and described in page 225 of this Memoir, has been faithfully lithographed by Vincent Brooks, Day, and Son, London. The autograph beneath the portrait was copied from a certificate of Dalton's, written about his sixty-third year.

ROSE HILL, CARLISLE

July 20, 1874.