45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON. 27 



33. " Great storms are invariably preceded by a fall in the barometer of 

 from '05 to '10 of an inch per hour. Storms from the eastward sometimes give 

 loss local warning, but they are well foretold by the increase of statical force. 

 Storms of a cyclonic character travel, it has been found, on an average about 

 20 miles an hour towards some point between NE. and SE., generally towards 

 the former. They, therefore, take about twenty-four hours to traverse the 

 British Isles, from the time of their commencement in the west of Ireland. 

 The east coasts may thus be warned one day in advance by the telegraph ; and 

 as the approach of a storm can be foreseen at the place threatened hours before 

 its advent, notice v of gales may usually be given from one to two days in 

 advance. As regards the exact time and locality, the prognostication of storms 

 must necessarily present much difficulty. The forecaster must be guided in 

 these respects rather by experience, to be gained by practice, than by princi- 

 ples ; little information can be given without going into a complete examination 

 of particular storms, each of which would present points of difference." 



Strachan'Si Weather Forecasts. 



NEGRETTI AND ZAMBRA'S 

 SELF-RECORDING ANEROID BAROMETERS. 



FIG. 28. 



34. This instrument registers automatically with ink upon a ruled paper 

 chart attached to a vertical cylinder revolved for seven days by means of a Clock 

 movement inside it. The fluctuations of atmospheric pressure act upon seven 

 Aneroid vacuum chambers, connected by an exceedingly simple mechanical con- 

 trivance to a long lever arm carrying the Pen, by which a magnified diagram is 

 produced upon the paper on the cylinder of the rise or fall or present height of 

 the Barometric column. These papers are ruled to represent inches and tenths 

 of the Mercurial Barometer Scale. A small Thermometer is mounted upon the 



base of the instrument. 



Price, in a Glazed Cabinet, as shown in fig. 28 .'.7100 



Kuled Papers, per Hundred, for above ... 18 



