SKETCH OF NIELS H. C. HOFFMEYER. 119 



on the distribution of atmospheric pressure not hitherto properly- 

 recognized, resulting in the mean minimum of pressure being 

 localized distinctly in the south of Iceland a minimum accom- 

 panied by two subordinate minima, one in Davis Strait and the 

 other in the Arctic Ocean, midway between Jan Mayen and the 

 Lofoden Islands. It was made plain, from typical charts giving 

 the mean of four winter months, that one or the other of these 

 minima plays the chief part, the other two being, for the time, 

 subordinate ; and that, according as one or the other of the mini- 

 ma predominates, so is the character determined, as regards mild- 

 ness or severity, of the weather of the winter of the regions sur- 

 rounding the north Atlantic. 



An illustration of his method of working is afforded by the 

 explanation he published of the causes of the cold weather that 

 prevailed over Europe in May, 1874. He showed that a maximum 

 of pressure had prevailed over northwestern and western Europe, 

 " stretching like a great screen " between the Atlantic and central 

 Europe, from Spitzbergen almost to Algiers, while the minimum 

 came partly from the arctic seas, and partly from the western 

 Mediterranean, with gradients steep toward the north and west, 

 Such a distribution of pressure must give rise to a cold polar 

 stream flowing over the greater part of Europe. In Vienna the 

 cold was greatest between the 16th and the 18th, and then the 

 high pressure began to travel eastward, with the production of a 

 great change, so that soon the pressure was lowest in the very 

 district where a few days before the maximum had existed ; and 

 the temperature rose. A similar cycle of phenomena occurred in 

 the next month. The author observed in this paper that areas of 

 high pressure are much more quiet and longer lasting than min- 

 ima, which travel rapidly, change their shapes, and throw off 

 secondary disturbances. 



The Meteorological Bulletin had become by the time of Hoff- 

 meyer's death a very important and complete publication. In 

 January, 1884, the number contained pressure results for thirteen 

 stations, temperature for one hundred and nine stations, and rain- 

 falls and other forms of precipitation for one hundred and fifty- 

 nine stations ; and these results were graphically shown on four 

 maps, accompanied with a full descriptive letterpress one map 

 giving the isobars for the month, another the isothermals, and on 

 the same map the mean temperature of each of the one hundred 

 and nine stations ; a third map, the miminum temperature at each 

 of the stations ; while the fourth map gave isohyetal lines, show- 

 ing the rainfall, with the amount at each of the one hundred and 

 fifty-nine stations entered in plain figures. 



The most important results deduced by Hoffmeyer from his 

 maps were contained in his pamphlet, Etude sur les Tempetes de 



