198 ROUND THE GREAT WHITE HORSE 



dangers of the mist, and numbers of these birds are 

 shot in small plantations. But though this unusual 

 tameness is partly due to their reluctance to leave 

 the landmark of the wood, they have also another 

 reason. Birds, looking down into the fog, as it lies 

 below them with the solid earth for a backing, have 

 far more difficulty in seeing objects beneath them, and 

 so avoiding danger from below, than we have in dis- 

 tinguishing their forms against the sky, which must 

 always be the lightest object even in thick fogs. The 

 writer and a friend had once some curious evidence of 

 the additional difficulty and danger to which fog 

 exposes birds. We had gone up on to the top of the 

 downs, where a long copse skirted the road, partly to 

 see the curious effect of these mists freezing on the 

 beech-trees, partly in hopes of shooting a couple of the 

 wood-pigeons which had been eating the turnip-tops in 

 safety during the open weather. , For some time, how- 

 ever, the mist was so black that we could see little, and 

 the pigeons, which were mostly in another and more 

 distant plantation, were afraid to move. Soon, how- 

 ever, though the fog hung as thickly as ever on the 

 ground, it was evident that there was a clearing in the 

 vapours higher up, for the tops of some poplar-trees 

 which grew by the side of the beech-copse, and rose 

 some thirty feet above the level of the rest, could be 

 seen bright with sunlight. These branches must have 

 stood out from the dark sea of mist as trees do in a 

 flood, and probably presented some such appearance to 

 the pigeons. For the flocks, which soon began to fly 



