598 THE POPULAR SCIENCE MONTHLY. 



GLASS-MAKING. 



By C. HANFORD HENDERSON, 



PROFESSOR OF PHYSICS AND CHEMISTRY IN THE PHILADELPHIA MANCAL TRAINING SCHOuL. 



I.— A PANE OF GLASS. 



C^ CARLYLE ! " exclaimed Emerson, in his diary, at the time 

 ^^ " Sartor Resartus " was being republished in America, " the 

 merit of glass is not to be seen, but to be seen through ; but every 

 crystal and lamina of the Carlyle glass shows." 



With admirable precision this defines the proper function of a 

 pane of glass. Decorative art, in casting about for new fields of 

 conquest, has too frequently induced a contrary feeling ; but, after 

 all, a window-pane at its best is something to be seen through 

 and not to be seen. It is our means of looking out upon the 

 world and letting the sun look in upon us. The more perfectly, 

 then, it fulfills its function, the less evidence will it bear of its 

 evolution from such dull things as sand and lime and soda-cake. 

 Our window-pane is transparent in all things save its own his- 

 tory. It gives no hint of what it is made of, or how it is made. 

 It is, indeed, easier to look through it than it is to look into it. 

 If one look in the right direction, however — and in America this 

 means toward Pittsburgh — he will see, in the cluster of glass-facto- 

 ries which have gravitated toward the natural gas of that neigh- 

 borhood, a side of industrial activity possessing much interest. 

 The brilliant pane of glass itself tells no stories, but the white-hot 

 furnaces and pots of molten metal, the active, hurried figures, and 

 the movements of rare dexterity that one sees at these places, are 

 far more communicative. 



They can well afford to publish their achievements, for about 

 few of its material products can the nineteenth century boast 

 with so much show of justice as about its window-glass. It is 

 true that past ages have produced quite as remarkable technical 

 results in other departments of industry, but in this one product, 

 at least, the present decade appears to be unique. Not even China 

 and Egypt, which have a standing claim of priority on all the 

 arts and sciences, dispute with the modern glass-maker. His tri- 

 umphs are without rival. 



Contrary legends are afloat, but they can be chased into no 

 fact: There is, for instance, a story current about the Queen of 

 Sheba and the wise King Solomon that quite puts into the shade 

 even the deceitfulness of riches. It is related by some gossipy 

 chronicler that, at the time of the famous visit, the royal audience 

 was so arranged that the queen and her suite in approaching were 

 obliged to pass over a floor of glass under which were flowing 



