SPECIAL BISECTIONS. 45 



(d) Used to signify that the direction in which the upper 

 current was moving could not be determined on 

 account of the sky being either perfectly clear or 

 entirely overcast. 

 The first (a) is the correct use. 



7. Want of full and proper records of the direction of the 

 wind, some observers recording the direction only after each 

 change, and then omitting it so long as -it continues the same, 

 merely inserting a figure to denote the force. It is better to 

 make the record in full. Other observers record the direction 

 towards which the wind or clouds are moving instead of indicating 

 that/rom which they come. A wiND/rom the North, or CLOUDS 

 moving from the North, are to be denoted by N, and from the 

 South by S, &c. 



8. Different kinds of thermometers or different exposures used 

 for the dry and wet-bulb thermometers, so that the observations 

 are not comparable readily, if at all. 



9. Diversity in the use of the dash and the^sign (") as follows : 



(a) To signify that the entry next above is to be repeated. 



(b) To signify that the entry next to the left is to be re- 



peated. 



(c) To signify that the entry next preceding in the order 



of time is to be repeated. 



(d) To signify nothing at all, but merely to fill a blank. 

 The use of these characters has caused much trouble in the 



reduction, and the true remedy would be to avoid them altogether, 

 by making each record complete in itself. 



10. Illegibility of the records, either from defective chirography 

 or from being entered in pencil marks and partially erased. 



