1 British Association Report for 1853.

2 The original photographs produced by M. Niepce are still preserved in good condition, and were last year exhibited at the Royal Institution.

3 "Philosophical Magazine," February, 1843.

4 Brewster's EncyclopÆdia, article "Kaleidoscope."

5 "The Stereoscope: its History, Theory, and Construction," by Sir David Brewster.

6 Primary signals are those in which the letter indicated is represented by a single deflection of the needles in either direction. A single needle telegraph can have only two primary signals, one to the right and one to the left; all the other letters being indicated by repeated deflections. In several instances four deflections are required to signal a single letter.

7 "Manual of Electricity," p. 251; and Reports of the Proceedings of the British Association for 1851 and 1854.

8 "Manual of Electricity," second edition, p. 247.

9 "Treatise on Coal Gas," by Samuel Clegg, jun.

10 See article, "Steam Carriages," page 35.

11 It is stated in Mr. Clegg's "Treatise on Coal Gas," that Mr. Clegg, sen., lighted the cotton mill of Mr. Henry Lodge, at Sowerby Bridge, near Halifax, a fortnight before the mill of Messrs. Phillips and Lee was so lighted. A friendly spirit of emulation is said to have existed between Mr. Murdoch and Mr. Clegg in lighting those two mills with gas, each one endeavouring to complete the work before the other.

12 The facility with which a supply of carburretted hydrogen gas can be obtained from gas works, induces aeronauts to fill their balloons with it rather than be at the trouble and expense of making hydrogen for the purpose; but the ascending power of the balloon is thereby greatly diminished.

13 Journal of Gas Lighting, vol. ii.

14 Mr. Hearder, of Plymouth, affords a remarkable instance of the successful pursuit of science under difficulties. He lost his sight in his youth by an accidental explosion during some chemical experiments, but instead of being disheartened by that calamity, he has continued to pursue his investigations with unabated vigour, and has succeeded in throwing much light on many of the recondite properties of electricity, by admirably contrived experiments, which were conducted with unremitting perseverance at great expense. He has been in the habit of delivering lectures at the Plymouth Institution, and other Institutions in Devon and Cornwall; and those who witness the skilful manipulation of his experiments can scarcely suppose that he is blind.

15 This statement does not adequately represent the reduction in price; for each volume, sold at 5s., contained a volume and a half as originally published, besides Sir Walter Scott's notes; and the cheap volumes were illustrated with steel engravings.

16 If the number of sheets of paper used in printing these works were laid side by side, they would extend nearly fifty thousand miles!

17 "L'Art de la Lithographie;" par M. Aloys Senefelder, Inventeur de l'Art Lithographique. Munich, 1859.

18 Book of Ecclesiastes i. 10.