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of the apple crop is about October first, and probably none which are 

 raised for export are gathered before September lirst There is, there- 

 fore, a period of from two to three months in which the average rainfall 

 is about three inches per month, a quantity amply sufficient to wash 

 away all traces of the spraying substances from the fruit and the leaves. 



In the summer of 1896 I made the following experiment. Having 

 built a small platform in the crotch of a large old apple tree, about fif- 

 teen feel from the ground, I took a two-gallon pailful of Paris green 

 mixture up to the platform about three times a week and sprayed the 

 whole tree from this platform, alternating occasionally with a solution 

 of sulphate of copper. At least half of the sprayings were of Paris 

 green. This mixture was so strong as to destroy some of the smaller 

 branches near the centre of the tree The sprayings were continued 

 till at least a dozen doses had been applied between May 15 and June 15 

 and the canker worms were pretty thoroughly destroyed. A good crop 

 of unusually fair apples began to appear, and were of three kinds, 

 Dutch codlings, Gravensteins and Danvers sweets The early apples 

 were picked about September 5 and the late sweets about October 5 or 

 later. Several of these were selected, of two kinds, together with some, 

 of the leaves, and were submitted to the State chemist for analysis, and 

 he reported that not the slightest trace of either arsenic or copper could 

 be found in them. 



It should, however, be borne in mind that Paris green is a deadly 

 poison, and when used on the farm, either for destroying the pests of 

 fruit trees or potatoes or even larger vermin, like rats and mice, the 

 greatest care should be taken to put the supply of poison out of the 

 reach of children and of animals. 



In what points do these general branches, agriculture and public 

 health, resemble each other? 



In point of usefulness to the community, agriculture and public health 

 have a great deal in common. Agriculture provides the means where- 

 with life is sustained, the sustenance essential to the continuance of the 

 human race. Nine-tenths of all the food used throughout the world is 

 the product of agriculture. How essential it is, therefore, that this most 

 useful branch should be developed in the most thorough manner and 

 maintained in the most perfect degree. 



As it is true that agriculture maintains life, it is also true that public 

 health or hygiene protects life. Although the term preventive medicine 

 is of comparatively recent origin, the practical application of the science 

 is by no means new. Moses applied it many centuries ago in the pre- 

 ventive treatment of leprosy and in the management of camp life. In 

 the Middle Ages nineteen thousand lazarettos were necessary to provide 

 shelter in continental Europe for the outcasts from this disease. Dr. 

 Jenner applied it when he introduced the practice of vaccination for the 

 prevention of small-pox, a hundred years ago. But it is only within the 

 past half century that systematic and careful study and attention have. 

 I icen given to public hygiene, with the view of training young men in 

 the BCience of preventive medicine or the art of prolonging life. It is 

 a fact capable of easy demonstration that, since careful attention has 



