Febbuabt 19, 19091 



SCIENCE 



289 



mental forms of aerial craft will likely be 

 developed, and that the lighter-than-air 

 type will be the burden-bearing machine 

 of the future, whereas the heavier-than-air 

 type will be limited to comparatively low 

 tonnage, operating at relatively high ve- 

 locity. The helicopter type of machine may 

 be considered as the limit of the aeroplane, 

 when by constantly increasing the speed 

 the area of the supporting surfaces is con- 

 tinuously reduced until it practically dis- 

 appears. We may then picture a racing 

 aeroplane propelled by great power, sup- 

 ported largely by the pressure against its 

 body, and with its wings reduced to mere 

 fins which serve to guide and steady its 

 motion. In other words, starting with the 

 aeroplane type, we have the dirigible bal- 

 loon on the one hand as the tonnage in- 

 creases, and the helicopter type on the other 

 extreme as the speed increases. Appar- 

 ently, therefore, no one of these forms will 

 be exclusively used, but each will have its 

 place for the particular work required. 

 Geobge 0. Squier 



MOSQUITO EXTERMINATION WORK IN 

 NEW JERSEY 



Professor John B. Smith, in his report to 

 the governor on the work carried on under the 

 law of 1906, shows that up to the end of the 

 summer of 1908 there had been drained 20,292 

 acres of salt marsh extending from the Hack- 

 ensack Eiver to the mouth of Toms Eiver on 

 Barnegat Bay. To accomplish this, required 

 2,Y23,974 feet of ditching, put in at an actual 

 cost of $44,058, some $12,000 being expended 

 for administration, surveys and other work 

 necessary to control the actual carrying out of 

 the contracts. 



During the same period of two years munici- 

 palities throughout the state have joined in 

 the mosquito crusade, and have expended con- 

 siderable sums of money for local work in 

 eliminating breeding areas. The work is all 

 in the direction of permanent improvement 

 and of destroying the breeding localities. Oil- 

 ing and temporary work is done only when it 



is necessary to destroy a brood of wigglers 

 that might otherwise hatch before permanent 

 work can be done. 



The results have been very gratifying and 

 the migrating marsh mosquitoes were almost 

 entirely absent during most of the summer 

 from the larger cities where drainage work 

 had been done in 1907 or earlier. It devel- 

 oped in the course of the work that the eggs 

 of these salt marsh species retain their vitality 

 for a very long period and that for at least 

 three years after a marsh is drained, there 

 may be ever lessening broods of larvae found 

 whenever it becomes water-covered by freshet 

 tides or heavy rains. This was interestingly 

 shown by examinations of marsh mud, from 

 areas drained for different periods, and count- 

 ing the eggs and egg shells on the samples. 

 It is, therefore, a rather slow process to com- 

 pletely clean up such areas, because a few 

 specimens developing under favorable circum- 

 stances will provide a small stock of eggs that 

 require three years or more to work out alto- 

 gether. In the areas drained in 1904, how- 

 ever, practically no eggs were found except in 

 the deepest depressions, and even in these they 

 were very few in number and much scattered. 



The season of 1908 was remarkable for the 

 excessive rainfall in early spring, which pro- 

 vided breeding areas for the early brood, far 

 beyond usual conditions, and these afterward 

 concentrated in cisterns, water-barrels, sewer 

 catch-basins and similar localities so that 

 cities were much troubled by them in the 

 entire region where these excessive spring 

 rains prevailed. 



If the legislature now in session provides 

 suflBcient means, it is expected that the drain- 

 age work can be carried to Great Bay during 

 the season of 1909, and in the cities the local 

 committees are already providing against a 

 duplication of last season's experience with the 

 house mosquito. 



TBE AMERICAN MUSEUM OF NATURAL 

 HISTORY 



The annual meeting of the trustees of the 

 American Museum of Natural History was 

 held on Monday, February 8. The following 

 officers were elected: Henry Fairfield Osborn, 



