Traegerwellblech and Asphalt. 79 



Various devices have been resorted to, and many are the 

 substances that have been put to the test in repeated 

 attempts to solve the problem of protecting buildings against 

 the inroads of moisture from the three sources I have 

 named; notably among them are copper, lead, zinc, iron, 

 glass, cement, and asphalt. From among these asphalt, 

 with various combinations of other substances, has proved 

 hitherto the best protection; and I may note, in passing, that, 

 not to mention other firms, that of Messrs. Busscher and 

 Hoffmann have made the manufacture of watertight building 

 materials of asphalt a speciality. 



The advantages possessed by this latter material are, 

 briefly, these : — 



1. Asphalt is not absorbent, and capable of resisting 

 the action of water in so far as our present purpose is 

 concerned. 



2. Its elasticity and homogeneity renders it capable of 

 being laid in successive layers, like a diaphragm over 

 irregular surfaces. 



3. Notwithstanding its ready adaptability to combine 

 with almost every known building material, experience 

 proves that no danger of disintegration is to be apprehended 

 from differences in expansion and contraction in the mass 

 protected by this medium. 



The following are the several varieties of this form of 

 asphalt as at present prepared for building purposes : — 



Carbon de pierre (stone pasteboard) ; 



Asphalt felt ; 



Asphalt plates ; 



Asphalt bricks. 

 The material called carbon de pierre, stone-paper, or stone 

 pasteboard (German, Steinpappe), was invented by Dr. Faxe, 

 a gentleman of the Swedish Navy, who flourished in the last 

 century. During the first half of the present century, Dr. 

 Gully, an eminent Prussian engineer, and Mr. Busscher, 

 the father of the proprietor of the factory I have made 

 mention of, made that material a subject of earnest study 

 in Sweden and Finland, and eventually matured the project 

 for its manufacture in Germany. 



The carbon de pierre is used in the following manner : — 

 To the purlins are spiked boards, and upon these boards, in 

 distances of 3 feet 4 inches, are nailed battens of triangular 

 section — thus A ; the intervening spaces between these 

 battens are laid with separate sheets, the edges of which lie 



