vi 



tions taken at various places. He likewise showed that the variations 

 of this element from day to day are nearly the same over all the 

 world. 



For these discoveries the Keith Medal of the Royal Society of 

 Edinburgh was awarded to him. 



In his first volume of the " Results of the Trevandrum Observa- 

 tions " Broun has given an original and exhaustive investigation of 

 the influence of the sun and moon upon the direction of the magnetic 

 needle ; but his researches regarding the lunar-diurnal variation of 

 this element form perhaps the most original part of the volume. 

 Besides having claims to be considered an independent discoverer of 

 this variation, he has certainly increased our knowledge of its laws more 

 than any other magnetician. He showed that near the equator its 

 law in December was the opposite of that in June. His observation 

 that the lunar action was reversed at sunrise, and that it was much 

 greater during the day than during the night, whether the moon was 

 above or below the horizon, may be noted as peculiarly likely to throw 

 much light on the theory of the subject. 



Broun's discovery of the simultaneity all the world over of the 

 changes from day to day of the earth's horizontal force has already 

 been mentioned. Certain of these changes he found to be due to the 

 moon, while others had a period of nearly twenty-six days. These last 

 Broun attributed to solar action, and in discussing the subject, in 

 a memoir published in the " Philosophical Transactions " for 1877, 

 he found that the greater magnetic disturbances were apparently due 

 to actions proceeding from particular meridians of the sun. This 

 is a subject of very great importance, and its exact meaning has yet 

 to be discovered. 



In meteorology Broun has done some very important work. He has 

 shown the apparent simultaneity of the changes of mean barometric 

 pressure over a great part of the globe, and here too be has discovered 

 a period of nearly twenty-six days. 



He was the first to commence those systematic observations of 

 clouds at various altitudes that are now so common, and he has like- 

 wise pointed out certain relations between atmospheric motions and 

 the directions of the lines of equal barometric pressure. 



For his various researches one of the Royal Medals of this Society 

 was conferred on him in 1878. 



It is gratifying to be able to state that Her Majesty has been 

 graciously pleased to mark her sense of the labours of this distin- 

 guished physicist by bestowing upon his widow a pension of £75 per 

 annum. 



