This chart is divided vertically into thirteen months "m order to include the first month of the following year; Each month is further divided, 

 by the lighter lines, into periods of six daysreach,.except'insthe case of those monthshaving fewer- or more days than 30, when the last division 

 of the month may equal four> five^ or seven days. The ist, 6th, 12th, i8th, 24thjand last^days of theimonth fall on the vertical lines. The 

 transverse Jines represent tho'isialiDDS from which, they extend. A complete break,Iii#the. isothermal line opposite 'any station generally Indicates 

 that the temperature did not reach the isotherm at that station during the year. A, line cotisisting of dashes denotes a laclC of observations foe 

 the correspoTiding statiail. 



