The Open Air 



drooping for lack of soil, are sometimes seen there, 

 besides grasses. Ivy is familiar as a roof-creeper. 

 Some ferns and the pennywort will grow on the wall 

 close to the roof. A correspondent tells me that in 

 Wales he found a cottage perfectly roofed with fern 

 it grew so thickly as to conceal the roof. Had a 

 painter put this in a picture, many would have 

 exclaimed: " How fanciful! He must have made 

 it up; it could never have grown like that! " 

 Not long after receiving my correspondent's kind 

 letter, I chanced to find a roof near London upon 

 which the same fern was growing in lines along the 

 tiles. It grew plentifully, but was not in so flourish- 

 ing a condition as that lound in Wales. Painters are 

 sometimes accused of calling upon their imagination 

 when they are really depicting fact, for the ways of 

 nature vary very much in different localities, and that 

 which may seem impossible in one place is common 

 enough in another. 



Where will not ferns grow ? We saw one attached 

 to the under-side of a glass coal-hole cover; its green 

 could be seen through the thick glass on which people 

 stepped daily. 



Recently, much attention has been paid to the dust 

 which is found on roofs and ledges at great heights. 

 This meteoric dust, as it is called, consists of minute 

 particles of iron, which are thought to fall from the 

 highest part of the atmosphere, or possibly to be 

 attracted to the earth from space. Lightning usually 

 strikes the roof. The whole subject of lightning- 

 conductors has been re-opened of late years, there 

 being reason to think that mistakes have been made 

 in the manner of their erection. The reason English 

 roofs are high-pitched is not only because of the rain, 

 that it may shoot off quickly, but on account of snow. 



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