In 1702, ten years after the invention of the process by which plate glass is made, a mirror with a surface area of one metre cost 165 francs. In 1889 such a mirror costs 30 f. 25 c. A mirror with four metres of surface area cost, in 1702, 2,750 francs. In 1889 it costs 136 francs. When we come down to modern times and to the much larger mirrors produced of late years, the fall in prices is extraordinary. In 1873 a mirror with ten square metres of surface cost 1,200 francs. To-day such a mirror can be bought at St.-Gobain for 467 francs, showing a fall of nearly two-thirds in price within sixteen years! To-day the total production of polished plate glass in the world is estimated as follows:-- square metres England (4 companies) 900,000 Belgium (6 companies) 600,000 Germany (4 companies) 150,000 United States (7 companies) 500,000 France (not including St.-Gobain) 130,000 St.-Gobain 800,000 --------- Total 3,080,000 From this it will be seen that nearly one quarter of the plate glass of a world in which plate glass, like champagne, is rapidly ceasing to be a luxury and becoming a necessity, is produced at this ancient establishment. With a keen perception of the tendencies of this age St.-Gobain, of late years, has been fitting its machinery to produce the very largest plates of glass possible to be made. Go where you like, from the Eden Theatre in Paris to the Casino of Monte Carlo, from the new monster hotel at the Gare St.-Lazare to the enormous edifice which an enterprising firm of tradesmen has planted in the centre of the Corso at Rome, and the vast glittering sheets of silvered glass turned out from the great forges everywhere confront you. At the French Exposition of 1878 St.-Gobain enabled the 'fly gobblers' of two hemispheres to admire themselves in the most gigantic mirror ever made down to that date. It measured six metres and a half in height, by four metres and eleven centimetres in width, which gave it a surface area of 26 metres 12 centimetres. Naturally M. Henrivaux determined to surpass this prodigy in 1889, and to match the Eiffel Tower with a mirror. The Belgian rivals of St.-Gobain suspected this, it seems, and sent forth subtle persons to spy out the plans of the great French manufactory. These colossal plates of glass are cast upon immense 'tables' of metal, and by ascertaining the dimensions of the tables ordered for St.-Gobain the ingenious Belgians hoped to get the measure of the effort it would be necessary for them to outdo. In anticipation of this subtlety the director of St.-Gobain ordered two immense tables, and when these were sent to the manufactory, had them skilfully thrown into one. Upon the gigantic table thus prepared the grand mirror of the Exposition of 1889 was cast at the eleventh hour.