754 A MEMOIR OF ELIAS LOOMIS. 



Proft'ssor Esi)y lulopted — and theii'after adlu'i^Ml to — a iiioditication of 

 this iiH'tbod ol' iei)iesenting storm plieiioineiia, and 1 tbiiik meteorolo- 

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

 from 1842 to 1854, tlioii<;h tliey contained an immense aoeumnlation 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, l*rofessor Loomis drew on the ma[) 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 mai)s 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 througli all places where the barometer stood 0.2 of 

 an inch below the normal, and other lines through i)oints where the 

 barometer was 0.4 below, 0.(3 below, 0.8 below, etc. ; also lines were 

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

 above its normal height. The deviations of the barometric pressure 

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

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

 , of colois 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 .')0 degrees above the normal, oi- below 

 the normal. Arrows of proper direction and length represented the 

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

 successive mai>s lor the three or four days of the storm furnished to the 

 eye all its phenomena in a simple and most eifective 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 Service, and by weather-service bureaus in other countries. 

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

 has the suliject of a storm under consideration. Hut the greatest in- 

 ventions are oft-times the simplest, and 1 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 paper which con- 

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

 important paper in the history of that science. 1 regret that 1 can not 

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

 what .seemed to me an almost despairing expression made many years 

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

 work, as he looked out u[)on the confused massof observations already 

 made, and felt unable to say in what direction i)rogress was to be ex- 

 pected. Witli this 1 contrast the buoyant expresiiions of another officer 



