June 9, 1911] 



SCIENCE 



901 



tain, very frequently, small amounts of ar- 

 senic, as well as other substances whicli may 

 or may not have an injurious effect. It is 

 quite well known that small quantities of ar- 

 senic have a tendency to hasten the ripening 

 process in fruits. One instance of particular 

 interest has been noted. A certain shipment 

 of pears was wrapped with two different 

 brands of paper. The pears were of one 

 variety, all from one orchard, and were kept 

 under exactly the same conditions and treated 

 in every way the same, excepting that about 

 one half of the shipment was wrapped with 

 one brand of paper and the rest with another 

 brand. After the fruit had been in storage 

 for some time it was found that the ripening 

 process in one lot was much in advance of the 

 other; the other lot remained normal. After 

 an examination of the whole shipment it was 

 found that the condition of the fruit corre- 

 sponded exactly with the brand of paper used. 

 It would seem from this that fruit growers 

 should pay particular attention to the quality 

 of paper used for wrapping fruit as well as 

 the quality of arsenate of lead used in spray- 

 ing the fruit. 



P. J. O'Gaba 



TSE AMESICAN PHILOSOPHICAL SOCIETY 

 The annual general meeting of the society was 

 held in the hall of the society, Philadelphia, April 

 20, 21 and 22, at which about sixty papers were 

 presented on scientific and literary topics. 



President W. W. Keen, LL.D., and Vice-presi- 

 dent E. C. Pickering took turns in presiding at 

 the various sessions. 



It has been the custom for several years to 

 devote one half -day session to a symposium on 

 some special topic in science. This year the sub- 

 ject was ' ' Modern Views of Matter and Elec- 

 tricity, " and the following papers bearing on this 

 general topic were offered: "The Fundamental 

 Principles," by Professor D. F. Comstock, of 

 Boston; "Radioactivity," by Professor B. B. 

 Boltwood, of New Haven ; ' ' Thermionics, ' ' by 

 Professor O. W. Richardson, of Princeton; "The 

 Constitution of the Atom," by Professor H. A. 

 Wilson, of Montreal. The general conclusion 

 seems to be that the atom of matter, groups of 

 which compose the molecules of different sub- 

 stances, is built up of much smaller parts, known 



as electrons, identical with the smallest unit of 

 negative electricity. Sir J. J. Thomson's theory 

 of the atom assumes also a spherical form of 

 positive electricity, throughout which are im- 

 bedded the electrons in different numbers accord- 

 ing to the kind of atom. It was also explained 

 how it is possible to estimate the actual number 

 of electrons in an atom of any given kind. As 

 the inertia of an electron emitted from the atom 

 of a radioactive substance, such as radium, has 

 been experimentally proved to be a function of its 

 speed, the evidence is strong that all inertia or 

 mass may be electrodynamic in its nature. 



At the opening session on Thursday the fol- 

 lowing papers were read: 



Notes on Cannon: Fourteenth and Fifteenth Cen- 

 turies: Chakles E. Dana, Philadelphia. 

 The first absolutely reliable, contemporaneous 

 account we have of cannon is contained in an 

 edict, still to be seen, in Florence, Tuscany, dated 

 1326. What these cannon looked like or did we 

 shall never know, but with them begins the au- 

 thentic history of ordnance; back of them is only 

 legend. 



Powder was in those early days, as its name 

 implies, a dust; it contained the charcoal and 

 sulphur of to-day, as well as the saltpeter, but 

 far too small a quantity of the last, on account 

 of the difficulty in procuring it. The cost, in the 

 middle of the fourteenth century, was almost pro- 

 hibitive, cheap at twenty-five dollars a pound, in 

 money of to-day. 



The next mention of cannon is of some at the 

 Tower of London in 1338 ; amongst these were 

 several breech-loaders. Another, in the same year, 

 called a ' ' pot for hurling arrows, ' ' was the pride 

 of the arsenal of Eouen, France. The charge for 

 this mighty engine of war was less than an ounce 

 of the badly proportioned dust of that day — 

 termed powder. 



It is often asserted that three field-guns were 

 used by the English at Crecy, where, in 1346, they 

 gained so tremendous a victory. One must always 

 remember that a large body of English archers 

 was there present. Every man of them was a 

 dead-shot, firing ten or more arrows a minute 

 from Ms "longbow"; the effective range was two 

 hundred and fifty yards, every ' ' cloth-yard ar- 

 row" was an armor-piercing projectile. Of what 

 use three absurd pop-guns would have been it is 

 difficult to imagine. The interest is purely anti- 

 quarian, as these would have been the first field- 

 artillery mentioned in history. That cannon were 



