July 25, 1919] 



SCIENCE 



93 



Bureau, Mr. Gregg also classified tlie daily 

 weather maps of the North Atlantic for a ten- 

 year period into days when wind conditions 

 were excellent, g'ood, fair, or poor for the 

 journeys both ways and both routes. Grouping 

 the excellent and good days together, the 

 average number of days in May favoring New- 

 foundland to Ireland flight is 12, Newfound- 

 land to Portugal, 11, and return on both 

 routes, only 2. For June, the corresponding 

 figures are 10, 6 and 2. While on the average 

 there should be plenty of favorable days, in- 

 dividual months vary greatly. Thus, in July, 

 1906, there were 28 favorable days for the trip 

 to Ireland, but in July 190Y, only 4. 



Mr. Gregg's general conclusions are worth 

 quoting : 



CONCLUSIONS 



1. In the present stage of their development and 

 until improvements give them a much larger cruis- 

 ing radius than they now have, airplanes caji not 

 safely be used for trans^Atlantic flight except 

 under favorable conditions of wind and weather. 



2. Observations of conditions over as great an 

 area as possible, and particularly along and near 

 any proposed course, should therefore be available 

 at as frequent intervals as possible, these observa- 

 tions to include free-air as well as surface condi- 

 tions. 



3. With such observations at hand the meteorol- 

 ogist is able quickly to determine the current, and 

 probable future, wind conditions along a proposed 

 route and to advise an aviator as to the suitability 

 of a day for a flight. 



4. If a day is favorable, the meteorologist is 

 able to indicate the successive directions toward 

 which an airplane should be headed in order to 

 keep to any desired course; also, to calculate the 

 assistance that will be furnished by the winds. 



5. Inspection of marine weather maps shows 

 that at an altitude of 500 to 1,000 meters condi- 

 tions are favorable for an eastward trip approxi- 

 mately one third of the time, the percentage being 

 slightly greater along the northern than along the 

 southern route. At greater altitudes the percent- 

 age of favorable days materially increases, espe- 

 cially along the northern route. For the westward 

 trip the percentage of favorable days is so small 

 as to make trans-Atlantic flight in this direction 

 impracticable until the cruising radius of aircraft 

 is increased to such an extent that they are rela- 

 tively independent of wind conditions. 



6. AU things considered, conditions for an east- 

 ward flight are most favorable along the northern 

 course; for a westward flight they are most favor- 

 able along the southern course; that is, the pre- 

 vailing westerlies are less persistent along this 

 course than farther north. 



7. There seems to be little cjioice as to season, 

 for, although the prevailing westerlies are stronger 

 in winter than in summer, yet, on the other hand, 

 stormy conditions are more prevalent in winter, 

 and the net result is about an equal percentage of 

 favorable days in the two seasons. Moreover, the 

 greater fog percentage in summer just about off- 

 sets the greater percentage of cloudiness in winter. 

 Fog is a disadvantage chiefly because of its inter- 

 ference in making observations with drift indica- 

 tors. The Newfoundland fogs in general are of 

 small vertical extent and do not extend far inland. 

 They should not, therefore, prove a hindrance to 

 landing, if the landing field is located some dis- 

 tance from the coast. 



8. Most important of all, there is need for a 

 comprehensive campaign of meteorological and 

 aerological observations over the North Atlantic in 

 order that aviators may be given data for whose 

 accuracy the meteorologist need not hesitate to 

 vouch, instead of information based on so small a 

 number of observations, particularly of free air 

 conditions, that the deductions, including some of 

 those in this paper, are assumed and not proved, 

 are given with caution, and are ' ' subject to change 

 without notice. ' ' 



How some of these conclusions have worked 

 out in actual practise is being discussed in 

 contributions to be published in the Monthly 

 Weather Review. 



Charles F. Brooks 



Washington, D. C. 



SPECIAL ARTICLES 



A CHART OF ORGANIC CHEMISTRY, 

 AROMATIC SERIES 



The following chart was made and is used 

 in connection with the elementary organic 

 chemistry course given at the university. The 

 heavy type lines in the benzene rings in- 

 dicate the double bonds while the light lines 

 indicate the single bonds. In order to em- 

 phasize certain characteristic groups, position 

 of substituents in the rings, etc., red letter- 

 ing was used. In the following miniature 



