NOTES. 



2 55 



How Suctorial Insects feed. It is com- 

 monly supposed that dipterous, or two- 

 winged insects, never eat the pollen of 

 plants, their mouths being destitute of 

 mandibles, and fitted only with a tube, or 

 proboscis, for sucking up juices. That this 

 statement does not hold good for all insects 

 belonging to this order, is shown from ob- 

 servations lately made by Alfred W. Ben- 

 nett. This distinguished entomologist has 

 found that at least insects of the family 

 Syrphidce (hoverer-flies) eat the pollen of 

 plants. He has examined, under the micro- 

 scope, the contents of the abdomen of two 

 species of syrphidae, which he found to be 

 colored a bright orange, owing to the pres- 

 ence of enormous quantities of aster-pol- 

 len. That the grains of pollen are not ac- 

 cidentally taken up, but form an actual 

 article of food, is proved by their being 

 found in every stage of digestion, the fluid 

 contents of the grains being apparently the 

 nutritive substance, and the skins being ul- 

 timately excreted. During the last spring, 

 Mr. Bennett captured Eristalis tenax (the 

 drone-fly) on the flowers of the sloe. The 

 abdomen of the insect was full of pollen- 

 grains, belonging to at least three kinds of 

 plants sloe, dandelion, and probably fuch- 

 sia. 



Oxidation retarded by Molecular Vibra- 

 tions. A paper was read, at the American 

 Association meeting, on "Mechanical Vibra- 

 tion retarding Rust," by Prof. S. S. Halde- 

 man. The iron track of a railroad is but 

 little subject to oxidation, while iron rails 

 piled alongside quickly rust. If traffic be 

 suspended on a railroad for a day, and, in 

 the mean time, a rain of some hours' dura- 

 tion fall on the rails, they soon show 

 signs of rust. From these facts Prof. Hal- 

 deman argues that, in chemical combina- 

 tion, mechanical vibrations may interfere 

 with the molecular arrangement of the ele- 

 ments. He would, however, have these 

 casual observations submitted to the test 

 of experiment. A discussion followed, in 

 the course of which it was suggested that 

 possibly the oil employed upon locomotives 

 might be more or less spread in a thin film 

 over rails in use, and thus prevent their 

 oxidation. This view met with no favor. 

 Prof. Van der Weyde was quite certain that 



the suggestion of Prof. Haldeman had refer- 

 ence to a fact in physics. Molecular vibra- 

 tions do undoubtedly tend to prevent rust : 

 a saw hung up unused would soon grow 

 rusty, whereas if used it would keep bright ; 

 and the observation is universal with regard 

 to mechanical tools. 



The Metric System of Weights and Meas- 

 ures. On the last day of the Hartford meet- 

 ing of the American Association, President 

 Barnard, of Columbia College, delivered an 

 address on the " Metric System." He pre- 

 dicted that the metric system will become 

 the sole system of weights and measures in 

 use throughout civilized nations before the 

 year 1900. In France, Holland, Belgium, 

 Spain, Portugal, Italy, Switzerland, the 

 German Empire in fact, all Europe, ex- 

 cept Scandinavian countries and England, 

 and in all America, except the United 

 States, the metric system has been adopt- 

 ed. Even in the Indian empire of Great 

 Britain the metric system has been adopt- 

 ed, and that system has been legalized, 

 though not yet adopted, in Great Britain 

 and here. At the Vienna Metrological 

 Congress, every delegate, though repre- 

 senting nearly every country on the civil- 

 ized globe, voted for the metric system. 



NOTES. 



The American Society of Civil Engineers 

 have appointed a committee to report on 

 plans for 1. The best means of rapid pas- 

 senger transit ; and, 2. The best and cheap- 

 est method of delivering, storing, and dis- 

 tributing goods and freight in and about 

 the city of New York. The society ask for 

 suggestions from all eivil engineers, and 

 others who may be possessed of any infor- 

 mation touching the subject of their inves- 

 tigations. The secretary of the society is 

 G. Leverich, and his address is 63 William 

 Street. 



Last December a telegram was sent 

 from New York to London, and an answer 

 received in 30 minutes actual time. The 

 distances traversed were as follows : from 

 New York to Heart's Content, N. F., 1,300 

 miles ; cable, 2,000 ; Valentia to London, 

 300 miles. Each of the telegrams, there- 

 fore, traveled 3,600 miles, and passed 

 through the hands of 18 persons. 



As international exhibition has'positive- 

 ly been decided upon in China, and a com- 



