(Im-iiiii 'ritnndi'rxturtns, and on the Brontometer. 0") 



It is provided with endless paper, 12 in. wide, travelling under the 

 various recording pens at the rate of T2 in. per minute, or 6 ft. per 

 hour. This is about 150 times faster than is usual in meteorological 

 instruments, and enables the time of any phenomenon to be read off 

 with certainty to a single second of time. 



The traces are made in aniline ink by a series of seven Richard 

 pens. 



The first pen is driven by the clock which feeds the paper, so that 

 the time scale and the paper must go together. The pen usually 

 produces a straight line, which serves as the base line for all measure- 

 ments, but at 55 seconds after each minute the pen' begins to go, at 

 nu angle of about 45, one-tenth of an inch to the left, and at the 

 sixtieth second it flies back to its original position. 



The second pen is driven by one of Richard's Anemo-cinemographs, 

 a name which they have given to a pattern of anemometer not yet 

 kuown in England. The external portion has some resemblance to 

 the ordinary windmill governor, but it differs from it in that the 

 plates are curved, not flat ; they are made of aluminium, and are so 

 light that they have little momentum, and have thus a great advant- 

 age over cups, which run on for many seconds after the wind force 

 has decreased or ceased. The fans make one revolution for each 

 metre of wind that passes, and send an electric current to the 

 brontometer, where it acts on an electro-magnet, and tends to draw 

 this (2nd) pen towards the left ; but a train of clock work is constantly 

 tending to draw the pen to the right, the joint result being that the 

 pen continuously shows, not the total motion (as is the case with most 

 anemometers), but the actual velocity almost second by second. It 

 does this certainly with an error of less than five seconds, for the 

 fans will stop dead in less than that time, and the clockwork train 

 will bring the pen from indicating a velocity of 70 miles an hour to 

 20 miles an hour in three seconds, and down to a dead calm in se\'en 

 seconds. The trace will thus resemble that of a pressure anemometer, 

 but with a much more open scale than was ever before available. 



The third pen is actuated by a handle, and can be set at zero or at 

 1, 2, 3, or 4 spaces from it. The author's original idea was, partly 

 by watching a storm-rain-gauge, and partly by estimation, to decide 

 on the intensity of the rain and to indicate that intensity by moving 

 the pen further and farther from zero as the fall becomes heavier. 

 Experience alone will show whether that is, or is not, superior to 

 moving it one step for each yj^th f an i ncn f fallen rain, which can 

 be done by making a Crosley rain-gauge send a current into the room 

 where the broutometer is placed, and strike a bell there. In a heavy 

 storm there will, however, be so much for the observer to do, that 

 very probably count would be lost. It may, therefore, be necessary 

 ID make it act automatically. 



VOL. XLYIII. F 



