1HE HA11031ETER AXD THE WEATHER. ISO 



a correction for elevation is necessary. When the height of 

 the place is known this correction may be made by adding one 

 tenth of an inch to the actual reading for every 85 feet of 

 elevation up to 510 feet ; the same for every 90 feet between 

 510 and 1140 feet, for every 95 feet between 1140 and 1900 

 feet, and for every 100 feet above this and within our moun- 

 tain limits. This simple and easy rule is sufficiently accurate 

 for practical purposes. Thus, a barometer on Bray Head, or 

 any place 800 feet above the sea, would require a correction of 

 six tenths for the first 510 feet, and a little more than three 

 tenths more for the remaining 290 feet. Therefore, if such 

 a barometer registered the pressure at 92 T * ff , the proper sea- 

 level reading would be a little above 30 inches. 



The most important prognostications of the barometer are 

 those afforded by what is called the ** barometric gradient or 

 incline," showing the up-hill and down-hill direction of the 

 atmospheric inequalities ; but this can only be ascertained by 

 comparing the state of the barometer at different stations at 

 the same time. Thus, if the barometer is one fourth of an 

 inch higher at Dublin than at Galway, and the intermediate 

 stations show intermediate heights, there must be an atmos- 

 pheric down-hill gradient from Dublin to Galway ; Dublin 

 must be under the upper and Galway under the lower portion 

 of a great atmospheric wave or current. It is evident that 

 when there is thus more air over Dublin than over Galway, 

 there must follow (if nothing else interferes) a flow of air from 

 Dublin toward Galway. It is also evident that, in order to 

 tell what else may interfere, we must know the atmospheric 

 gradients beyond and around both Dublin and Galway, and 

 for considerable distances. 



We are now beginning to obtain such information by organ- 

 izing meteorological stations and observatories, and transmit- 

 ting the results of simultaneous observations by means of the 

 electric telegraph to certain head-quarters. 



The subject is occupying much attention, and the managers 

 of those splendid monuments of British energy our daily 

 newspapers are publishing daily weather charts, and there- 

 fore a few simple explanations of the origin, nature, and sig- 

 nificance of such charts will doubtless be appreciated by our 

 readers. 



The grand modern improvement of the barometer, the ther- 

 mometer, the anemometer, the pluviometer, etc., is that of 

 making them " self -registering." \Vc are told that Cadmus 



