754 A MEMOIR OF ELIAS LOOMIS. 



Professor Espy adopted — aud thereafter adhered to — a modification of 

 this method of representing storm phenomena, and 1 think meteorolo- 

 gists will agree with me in my opinion that Professor Espy's four reports 

 irom 1842 to 1854, though they contained an immense accumulation of 

 facts, were because of this radical defect of presentation almost useless 

 to meteorological science. 



In the discussion of the storms of 1842, instead of the line of minimum 

 depression of the barometer, Professor Loomis drew on the map a series 

 of lines of equal barometric pressure, or rather of equal deviations 

 from the normal average i)ressure for each place. A series of maps rep- 

 resenting the storm at successive intervals of twelve hours were thus 

 constructed, upon each of which was drawn a line through all places 

 where the barometer stood at its normal or average height. A second 

 line was drawn through all places where the barometer stood 0.2 of 

 an inch below the normal, and other lines through points where the 

 barometer was 0.4 below, 0.0 below, 0.8 below, etc. ; also lines were 

 drawn through those points where the barometer stood 0.2, 0.4, 0.6, etc., 

 above its normal height. The deviations of the barometric i)ressure 

 from the normal were thus made prominent, and all other phenomena of 

 the storm were regarded as related to those barometric lines. A series 

 of colors represented respectively the places where the sky was clear, 

 where the sky was overcast, and where rain or snow was falling. A 

 series of lines represented the places at which the temperature was at 

 the normal, or was 10 or 20 or 30 degrees above the normal, or below 

 the normal. Arrows of proper direction and length represented the 

 direction and the intensity of the winds at the different stations. These 

 successive maps for the three or four days of the storm furnished to the 

 eye all its phenomena in a simple and most effective manner. 



You have no doubt, most of you, already recognized in this descrip- 

 tion the charts, which to-day are so common, issued by the United States 

 Signal Servi(;e, and by weather-service bureaus in other countries. 

 The method seems so natural, that it should occur to any person who 

 has the subject of a storm under consideration. But the greatest in- 

 ventions are oft-tinjes the simplest, and I am inclined to believe that the 

 introduction of this single method of representing and discussing the 

 phenomena of a storm was the greatest of the services which our col- 

 league rendered to science. This method is at the foundation of what 

 js sometimes called •' the new meteorology," and the jiaper which con- 

 tains its first presentation stands forth, I am convinced, as the most 

 iujportant paper in the history of that science. I regret that I can not 

 aid my memory by quoting the exact words, but I remember distinctly 

 what seemed to me an almost des[)airing e.\i»ression made many years 

 ago by one who had high responsibility in the matter of meteorological 

 work, as he looked out upon the confused mass of observations already 

 made, and felt unable to say in what direction progress was to be ex- 

 pected. With this I contrast the buoyant expresaions of another ofticer 



