CORNISH VIADUCTS. 219 



timbers, tliey are instructed to run immediately for the wet 

 swab, and beat out the fire before it has become too large 

 to be manageable. Such cases have only occurred once or 

 twice, however ; and the tubs of water, being sunk into the 

 ground, and as a rule overgrown with long grass, now serve 

 to form a chilly trap for the unwary pedestrian, who uncon- 

 sciously ventures near them. The average life of the timber 

 is about eighteen years, — some more, some less. 



The masonry of the piers varies very much with the 

 locality. Some of them, those in the Grlynn Valley, for 

 instance, are admirably built ; but others, such as those of 

 the old Moorswater Viaduct, are rather poor. The stones 

 are, as a rule, small ; but this is only natural at a time 

 when they did not have the appliances which we now 

 possess, and had to haul all their materials up by hand or 

 horse cranes, instead of the handy steam derrick cranes 

 which we find so useful now-a-days. There is scarcely a 

 straight viaduct throughout Cornwall. Doubtless this is in 

 great measure due to the necessarily sinuous nature of a 

 railway which has to be continually winding in order to 

 seek the easiest ground ; but the old builders seem almost 

 to have taken especial pains to put their viaduct on the 

 curve, when, as has been done in reconstruction, they might 

 easily have built it on the straight. 



The vibration on these viaducts as a train passes over 

 them is something rather larger than considerable. The 

 author himself has often been in one of the manholes which 

 project beyond the parapet at intervals, and has never quite 

 got over the feeling that he was going to be shot over the 

 side of the viaduct like a stone out of a catapult. 



Since 1871, fourteen of these viaducts out of the forty-two 

 ha\'e been replaced by more durable structures. Two have 

 been done away with altogether, one having been substituted 



