138 



THE POPULAR SCIENCE MONTHLY. 



poisonous property of the sting of bees lies 

 in the formic acid it discharges, whicli is also 

 "probably associated with some other toxic 

 agent." The idea that the bee invariably 

 dies after stinging is a vulgar error. " It 

 will, if allowed time, generally carry its 

 sting away by traveling round upon the 

 wound, giving the instrument a screw-move- 

 ment until it is free." More usually, how- 

 ever, the bee is not allowed time to travel 

 round, "and she loses not only the sting 

 and the venom-gland and sac, but also the 

 lower portion of the bowel, so that her death 

 follows in an hour or two." We are fur- 

 ther informed that no bee inflicts a wound 

 " until she has examined the nature of the 

 surface to be punctured, using a pair of 

 very beautiful organs called palpi, elabo- 

 rately provided with feeling hairs and thin 

 nerve- ends." 



Mr. Ediscn's Pyromagnetic Dynamo. — 



Mr. Edison, in his paper, at the American 

 Association, on the " Pyromagnetic Dyna- 

 mo," after describing the construction and 

 operation of the machine, said that the re- 

 sults thus far obtained lead to the conclu- 

 sion that the economy of production of elec- 

 tric energy from fuel by the pyromagnetic 

 dynamo will be at least equal to, and proba- 

 bly greater than, that of any of the methods 

 in present use. But the actual output of 

 the dynamo will be less than that of an 

 ordinary dynamo of the same weight. To 

 furnish thirty sixteen-candle lights in a 

 dwelling-house would probably require a 

 pyromagnetic generator weighing two or 

 three tons. Since, however, the new dyna- 

 mo will not interfere with using the excess 

 of energy of the coal for warming the house 

 itself, and, since there is no attendance 

 needed to keep it running, there would seem 

 to be already a large field of usefulness for 

 it. Moreover, by using the regenerative 

 principle in connection with it, great im- 

 provement may be made in its capacity, and 

 its practical utility may very probably equal 

 the interesting scieutiflc principle which it 

 embodies. 



Characteristics of Tropical Woods.— 



Professor R. II. Thur.ston, describing some 

 Nicaraguan woods in the American Associa- 

 tion, said that the tropical and sub-tropical 

 woods are distinguished usually by their ex- 



traordinary size, strength, hardness, and so- 

 lidity, as well as by durability, as against both 

 weather and the attacks of insects. About 

 thirty samples, selected simply by considera- 

 tions of convenience and previous acquaint- 

 ance from among an enormous number of 

 probably equally valuable genera, were sub- 

 jected by the author to special tests. Some 

 of them resembled in appearance and qual- 

 ity mahogany ; some, our own yellow pine ; 

 others, the oaks and other hard woods of 

 our forests, but excelled them in density, 

 strength, elasticity, and durability. While 

 they may prove of extraordinary value for 

 many purposes, they are often so hard to 

 work that their usefulness is likely to be 

 restricted. The Central American forests 

 ccntain an enormous store of timber of re- 

 markably fine quality. 



Exceptions to the Rale of Laissez- 

 Faire. — Professor Sidgwick read an elabor- 

 ate paper in the British Association on the 

 economic exceptions to the laissez-faire. Po- 

 litical economy, he said, as commonly un- 

 derstood, includes a general argument show- 

 ing how wealth tends to be produced most 

 amply and economically in a society in 

 which government confines itself to the 

 protection of person and property and the 

 enforcement of contracts not brought about 

 by force or fraud, leaving individuals free 

 to produce and transfer to others whatever 

 utilities they choose on any terms that may 

 be freely arranged. The argument is, briefly, 

 that in a society so constituted, the regard 

 for self-interest on the part of consumers 

 will lead to the effectual demand of the 

 things that are most useful, and the regard 

 for self-interest on the part of producers 

 will lead to their production at the least 

 cost. It is, however, now generally held 

 that the broad rule of "leave alone," to 

 which the argument points, must in practice 

 be limited by various exceptions. Two classes 

 of these exceptions are distinguished, viz. : 

 {a) those which arc due to the limitations 

 •under which abstract economic theory has 

 to be applied in the art of government ; 

 and {h) those which it is the more direct 

 business of economic theory to analyze and 

 systematize. In class (a) may be distin- 

 guished — (1) governmental interference to 

 regulate the education or employment of 

 children; (2) interference for the promo- 



