264 SCIENCE IN SHORT CHAPTERS. 



paths, from which nobody should deviate in the winter time. 

 Before the season for strolling in the grass returns, Nature 

 will have disposed of the fallen leaves. A partial remedy 

 may be applied by burning the leaves, then carefully dis- 

 tributing their ashes; but this is after all a clumsy imita- 

 tion of the natural slow combustion above described, and is 

 wasteful of the ammoniacal salts as well as of the heat. 

 The avenues of Bushey Park are not going so rapidly as 

 the old sylvan glories of Kensington Gardens, though the 

 same robbery of the soil is practiced in both places. I 

 have a theory of my own in explanation of the difference, 

 viz., that the cloud of dust that may be seen blowing from 

 the roadway as the vehicles drive along the Chestnut Ave- 

 nue of Bushey Park, settles down on one side or the other, 

 and supplies material which to some extent, but not suffi- 

 ciently, compensates for the leaf -robbery. 



The First Commissioner speaks of efforts being made to 

 restore life to the distinguished trees that are dying. Let 

 us hope that these include a restoration to the soil of those 

 particular salts that have for some years past been annually 

 carted away from it in the form of dead leaves, and that 

 this is being done not only around the " distinguished " 

 trees, but throughout the gardens. 



Any competent analytical chemist may supply Mr. Adam 

 with a statement of what are these particular salts. This 

 information is obtainable by simply burning an average 

 sample of the leaves and analyzing their ashes. 



While on this subject I may add a few words on an- 

 . other that is closely connected with it. In some parts 

 of the parks gardeners may be seen more or less ener- 

 getically occupied in pushing and pulling mowing-machines; 

 and carrying away the grass which is thus cut. This 

 produces the justly admired result of a beautiful velvet 

 lawn; but unless the continuous exhaustion of the soil 

 is compensated, a few years of such cropping will starve it. 

 This subject is now so well understood by all educated 

 gardeners that it should be impossible to suppose it to be 

 overlooked in our parks, as it is so frequently in domestic 

 gardening. Many a lawn that a few years ago was the 

 pride of its owner is now becoming as bald as the head 



