-SS Mr, J. Blackwairs Meteorological Observations [Feb. 



297, New Series), which, if generally adopted, would probably, 

 in a great measure, obviate the error and inconvenience arising 

 from the various and unsatisfactory modes of taking such obser- 

 vations, that are practised by the majority of meteorologists. 



I now trouble you with observations on the barometer, accom- 

 panied with a few remarks, hoping that they may prove useful 

 m pointing out the advantage of establishing a general unifor- 

 mity in the manner of conducting observations on the daily 

 pressure of the atmosphere. Should they appear suited to pro- 

 mote this desirable object, I shall feel obliged by your giving 

 them publicity. Your obedient servant, 



John Blackwall. 



A Series of Barometrical Observations made on Oct. 1, 1821, at 

 Crumpsally in Lancashire, with a Vieiv to determine the best 

 Method of obtaining the Extremes and Mean of the Atmosphe- 

 rical Pressure, during the Period of the natural Day. 



The methods of taking daily observations of the pressure of 

 the atmosphere which are generally practised, are so very 

 imperfect, and lead to such erroneous conclusions, that the 

 column of observations headed ** Barometer," is, perhaps, inva- 

 riably one of the most defective in every meteorological journal : 

 indeed, when we reflect how little is certainly known respecting 

 the causes that produce the local changes that are almost perpe- 

 tually taking place in the weight of the atmosphere, and how 

 fluctuating those causes are with which we are acquainted ; 

 when we consider also how few observations are usually made 

 in the day, and that still fewer are made during the night, we 

 shall cease to be surprised at the great inaccuracy of barome- 

 trical results. 



The laws that regulate the temperature of the atmosphere, at 

 least of that region of it about which our inquiries are more 

 immediately concerned, are better understood, and appear to 

 act with much greater regularity than those that influence its 

 pressure. So uniform indeed are their operations, that the 

 maximum of temperature is now known to occur about half-past 

 two o'clock, p. m. in our latitude, and the minimum about half 



