Produced by Clare Boothby, Josephine Paolucci and the Online Distributed Proofreading Team. LECTURES ON POPULAR AND SCIENTIFIC SUBJECTS BY THE EARL OF CAITHNESS, F.R.S. _DELIVERED AT VARIOUS TIMES AND PLACES._ Second Enlarged Edition. LONDON: TRÜBNER & CO., LUDGATE HILL. 1879. Ballantyne Press BALLANTYNE, HANSON AND CO. EDINBURGH AND LONDON CONTENTS. COAL AND COAL MINES SCIENCE APPLIED TO ART A PENNY'S WORTH; OR, "TAKE CARE OF THE PENCE, AND THE POUNDS WILL TAKE CARE OF THEMSELVES" PAST AND PRESENT MEANS OF COMMUNICATION THE STEAM-ENGINE ON ATTRACTION THE OIL FROM LINSEED HODGE-PODGE; OR, WHAT'S INTILT LECTURES ON POPULAR AND SCIENTIFIC SUBJECTS. _COAL AND COAL-MINES._ There are few subjects of more importance, and few less known or thought about, than our coal-mines. Coal is one of our greatest blessings, and certainly one originating cause of England's greatness and wealth. It has given us a power over other nations, and vast sums of money are yearly brought to our country from abroad in exchange for the coal we send. Nearly £17,000,000 is the representative value of the coal raised every year at the pit's mouth, and £20,000,000 represent its mean value at the various places of consumption. The capital invested in our coal-mining trade, apart from the value of the mines themselves, exceeds £20,000,000 sterling, and the amount of coal annually extracted from the earth is over 70,000,000 of tons. Taking the calculation of a working miner--J. Ellwood, Moss Pit, near Whitehaven--we may state, that if 68,000,000 tons were excavated from a mining gallery 6 feet high and 12 feet wide, that gallery would be not less than 5128 miles, 1090 yards, in length; or, if this amount of coal were erected in a pyramid, its square base would extend over 40 acres, and the height would be 3356 feet. There are grounds for believing that the produce of the various coal-fields of the world does not at present much exceed 100,000,000 of tons annually, and therefore our own country contributes more than three-fifths of the total amount. If we divide the coal-yielding counties of Britain into four classes, so as to make nearly equal amounts of produce, we find that Durham and Northumberland yield rather more every year than seven other counties, including Yorkshire. Derbyshire, again, produces more than eight other counties, and nearly as much as the whole of North and South Wales, Scotland, and Ireland--the yield of the latter being about 17,000,000 of tons, and that of the two first-named about 16,000,000 of tons.