NOT GENERALLY KNOWN, Familiarly Explained. A BOOK FOR OLD AND YOUNG. BY JOHN TIMBS, F.S.A. AUTHOR OF CURIOSITIES OF LONDON, AND EDITOR OF THE YEAR-BOOK OF FACTS. 17,996 25/5/76 Hugh 4.60 LONDON: PRINTED BY ROBSON, LEVEY, AND FRANKLYN, GENTLE READER, The sale of Ten Thousand copies of the present volume within Ten Months of its publication proves its object and character to have been warmly recognised by the public. As the taste of the day favours out-of-the-way reading, I have from its winding paths garnered into this little book a few of its stores for your special gratification. Although the result may not be recommended by the quaint fancy of the British Apollo, or the profundity of the Athenian Oracle,-the Notes and Queries* of other days,—I have not been unmindful of the value of pith and point upon subjects which you are not asked to take for granted in every instance, but in many cases to weigh and consider. 66 You may, perhaps, say, “ Your volume contains but a small portion of the Things not generally Known.'" Granted; but here are no fewer than FIVE HUNDRED groups of instances—in the main, from Popular Science and Antiquarianism: the Heavens and the Earth; the Sea and the Air; Sight and Sound; Life and Death; the Animal and Vegetable Kingdoms; the Origins of House and Home; the Festivals of our Calendar; historical glances at Laws and Customs; Dignitaries of Church and State; National Characteristics; Wonders of our Inventive Age; and a few Curiosities of the Art and Literature of early times. For This Edition has been corrected throughout; and several new Articles have been substituted for others of minor interest. this improvement I am indebted to friendly Correspondents. To conclude with Montaigne's words of charming simplicity: "I am wise enough to know, by the measure of my own abilities, that my soil is incapable of producing any of those rich flowers that are here set and growing; and that all the fruits of my own growth are not worth any one of them." I. T. *This work, commenced by my fellow antiquary and bibliographer, Mr. W. J. Thoms, in 1849, is now flourishing, not only learned in itself, but the source of much learning in others. To Mr. Thoms, however, as the originator of this "medium of intercommunication," authors as well as readers are specially bound to be grateful. ROOM IN WHICH THE EARTH WAS WEIGHED. The remarkable physical investigations by which certain philosophers have explained the Motion and ascertained the Density of the Earth, are glanced at in pp. 16 and 17 of the present volume; where is noticed the result obtained by Mr. Francis Baily, the astronomer, who, in 1838, within a small room, "contrived a pair of scales that enabled him approximately to weigh the vast sphere," at his residence, No. 37 Tavistock Place. The house stands detached from any other building, in a large garden some distance from the street, the roadway of which is macadamised. The building consists of one story only, and the room in which Mr. Baily conducted his experiments is at the N.E. angle of the first floor, and has only one window. It will be seen by the accompanying view that in the roof of the house is a small observatory; but the apartment we have to notice was preferred by Mr. Baily for the present experiments. Here he constructed apparatus differing in some respects from that with which Cavendish made his celebrated experiment, which Mr. Baily repeated under new circumstances, and with all the improvements of modern artists. In the apparatus used by Mr. Baily, there were two small balls, about two inches in diameter, carried on a rod suspended by two wires at a small distance from each other. The positions of these balls were viewed from a distance by a telescope. When this was done, large balls of lead, which moved on a turning groove, were brought near the small balls. Observations were then made on the small balls again, and in every case the small balls were put into a state of vibration, and moved towards the large balls. Now, knowing the size of the large balls, and their distance from the small balls, and knowing the size of the earth, and the distance of the small balls from its centre, the proportion of the attraction of the large balls on the small balls to the attraction of the earth on the small balls can be calculated; and from these results the mean density of the earth was found to be 5 67 times the density of water; that is, the average density of a cubic foot of the earth is more than 5 times heavier than a cubic foot of water. Having ascertained this result, and which agreed very nearly with the observations of Cavendish in the Schehallien experiments, all we want to know is, how many cubic feet there are in the earth. Now, taking the dimensions of the earth, as deduced from our best experiments, there are 259,800 millions of cubic miles in the earth; each cubic mile contains 147,200 millions of cubic feet; and each cubic foot weighs 5.67 times a cubic foot of water, which weighs about 62 lbs.; therefore, a cubic foot of the earth weighs about 354 lbs.; and 6,049,836 billions of tons are the weight of the whole earth.* Such readers as are desirous of becoming acquainted with Mr. Baily's 2153 experiments and their results, are referred to vol. iv. of the Transactions of the Royal Astronomical Society, to the published Report of the inquiry, or to the Year-Book of Facts, 1843. In this room also Mr. Baily frequently made other experiments, recorded in the Philosophical Transactions for 1838. On these investigations we need not here enlarge, our object being in this place to record historically, by way of anecdote and illustration, the building in which the earth was weighed, and its bulk and figure calculated. * This calculation, it will be seen, differs from that quoted at p. 17. |