238 MEMORIES OF MY LIFE 



experiment. Sir Andrew Noble kindly undertook to 

 make experiments for the Office, using- a io-pounder 

 gun that happened to be at the Armstrong Works at 

 Elswick. It had been designed especially for shoot- 

 ing at balloons, and was furnished with the necessary 

 spring for preventing harm from recoil. The results 

 were very good and consistent. The shells burst at 

 a constant height of about 9000 feet, and gave a 

 conspicuous and durable cloud of smoke, whose 

 drift could be easily seen and its rate calculated. I 

 designed a camera-obscura arrangement to do this 

 conveniently. The recorded interval of time between 

 the explosion as seen and as heard, was an adequate 

 measure of the distance of the shell-burst. It 

 could be ascertained with more care when desired, 

 and in more than one way. The cost of each shot 

 was about ten shillings. This method of observa- 

 tion was not followed up, as none of the existing 

 stations were thought suitable, and it was difficult 

 to find one that would be so, considering that easy 

 telegraphic connection with the Meteorological Office 

 was a necessity. Again, the method would be useless 

 in cloudy weather. It may possibly be of future 

 service for inquiries into the varying thickness of the 

 Trade winds in particular localities. 



Yet another attempt of mine may be mentioned. 

 Chiefly through the initiative of Admiral Fitzroy, 

 "Wind roses," as they are called, were calculated for 

 the various Ocean districts, bounded by lines of 

 latitude and longitude 10 degrees apart. They 

 formed adjacent rectangles or " squares " in the 

 maps used by seamen, which are always drawn on 

 " M creator's projection." The "rose" consists of 



