64 ON THE OLDER FORMS OF 



tained in an interlocking tile is to devise a form which 

 shall, by a series of ribs and corresponding depressions, 

 more thoroughly exclude water. In the United States, 

 tiles of this kind are being made besides the ordinary pan 

 and flat tile. It is not within the purposes of this paper to 

 speak of these in detail, as there are many kinds each pos- 

 sessing certain merits. 



I cannot forbear, however, alluding to a remarkable ex- 

 hibition of this material at the late Paris Exhibition which 

 suggested what an extraordinary industry might spring 

 up in this country if the merits of terra-cotta roofing-tiles 

 could be made more widely known. In this exhibition 

 there were not only a great many displays of the ordinary 

 flat tiles, but there were pan tiles as well as interlocking 

 tiles made of pressed glass, by the use of which dark 

 warehouses and attics might be made light. The tiles were 

 njade precisely like the terra-cotta ones, so that here and 

 there they could be introduced thus letting in gleams of 

 light in usually dark places, or the entire roof might be 

 covered with these glass tiles. There were also terra- 

 cotta tiles perforated to admit little squares of glass. 

 Graeber has called attention to ancient Greek tiles in the 

 temples at Phigalia, Athens, and other places, in which 

 the large flat terra-cotta tile was perforated for the pur- 

 pose, as he believes, of admitting light in dark places 

 under the roof. 



TILE-MAKING. 



In the course of this paper it has been shown that 

 throughout the world with the exception of our country 

 and Canada the use of terra-cotta roofing tiles is univer- 

 sal. There is no reason why they should not come into 

 general use in this country. There are large regions in 

 the United States, like Arizona, New Mexico and certain 



