1862.] on Meteorological Telegraphy. 453 



is offered, for about two days in advance, which is as far as may be 

 yet trusted generally, on an average, though at times a longer pre- 

 monition might be given, with sufficient accuracy to be of occasional 

 use. 



Minute, or special details, such as showers at particular places, or 

 merely local squalls, are avoided ; but the general or average charac- 

 teristics, those expected to be principally prevalent (with but few 

 exceptions) the following day, and the next after it, including the 

 nights — not those of the weather actually present — are cautiously ex- 

 pressed, after careful consideration. 



It may now be seen, after many months' trial, whether tolerably 

 correct forecasts of ordinary weather can be formed here sooner than 

 at distant, isolated places, where the published general Reports arrive 

 a day or two later ; and whether they are practically useful as con- 

 clusions available for the public. 



Ordinary variations of cloudiness, or clear sky, or rain, of a local, 

 or only temporary character, are not noticed usually. 



A broad general average, or prevalence, is kept in view, referring 

 to a day, or more, in advance, and to a district, rather than only to 

 one time or place ; should be remembered. 



The great practical difficulty is in separating the effect, on the 

 mind, oi present states of air, weather, and clouds, 'from abstract con- 

 siderations of what may be expected on the morrow, or next following 

 day. 



When in doubt, distrusting the indications, or inferences from 

 them (duly considered on purely scientific principles, and checked by 

 experience), the words " Uncertain" or " Doubtful," may be used, 

 without hesitation. 



As meteorological instruments usually foretell important changes 

 by at least a day, or much longer, we have to consider what wind and 

 weather may be expected from the morning observations, compared 

 with those of the days immediately previous, as indicative of the 

 morrow's weather, and of the day after, at each place — to take an 

 average of those expectations, for each district, collectively, m^rowp*; 

 and then to estimate dynamical effects. 



Outline maps, with movable windmarkers, and cyclone glasses or 

 horns, are useful in forecasting weather : and full consideration should 

 be given to the probable position, direction, extent, and degree of 

 progress of that centrical area, or node, round which the principal 

 currents usually circulate, or turn, as they meet and alter, combine 

 with, or succeed one another. 



Here dynamical considerations, with comprehensive comparisons of 

 statical facts, are most important; and to treat them even approxi- 

 mately well, with such quick despatch as is requisite, demands aptitude 

 and experience. 



Those who are most concerned about approaching changes, who 

 are going to sea, or on a journey, or a mere excursion ; those who 

 have gardening, agricultural, or other out-door pursuits in view — may 



