The Aylesbury Canal (a branch of the Grand Junction Canal) crosses the extreme western neck of the county, from S. of Puttenham to S. of Gubblecote.
GRAND JUNCTION CANAL AT TRING
The highest water level in England
The Grand Junction Canal is largely utilised by barges traversing the W. of Hertfordshire. It is conspicuous at Rickmansworth, Boxmoor, and Berkhampstead; it enters Bedfordshire near Marsworth Reservoir.
The New River was constructed by Sir Hugh Myddelton, a London goldsmith, in 1609-13, and is largely fed by springs at Chadwell near Hertford. Its course in Hertfordshire is mostly close to and parallel with that of the Lea. The New River caused the financial ruin of its projector; one of its shares is now worth a large fortune. The whole story of this undertaking is very interesting; but as the New River was cut in order to bring water to London that story belongs to a volume on Middlesex.
III. Climate
The chief elements of climate are temperature and rainfall. A general idea of the mean temperature and rainfall of Hertfordshire, both monthly and annual, may be gained from an inspection of Bartholomew’s Atlas of Meteorology (1899). From that work it appears that the mean annual temperature of the county, if reduced to sea-level (that is, the theoretical mean for its position) would be 50° or a little above it, but that the actual mean varies from 46°-48° on the Chiltern Hills to 48°-50° in the rest and much the greater part of Hertfordshire; also that the mean annual rainfall is between 25 and 30 inches, the latter amount only being approached towards the Chilterns. Thus altitude is seen to have a great effect on both these elements of climate.
Hertfordshire is hilly though not mountainous, a great extent of its surface being considerably elevated above sea-level, with a general south-easterly inclination; it has a dry soil; is well watered with numerous rivers of clear water—already enumerated—chiefly derived from springs in the Chalk; is well but not too densely wooded; and its atmosphere is not contaminated by manufacturing towns. It thus maintains the reputation for salubrity which it gained more than three centuries ago, our earliest county historian, Norden, remarking on the “salutarie” nature of the “aire”.
Observations taken at the following meteorological stations during the twelve years 1887 to 1898 have been printed annually in the Transactions of the Hertfordshire Natural History Society, and a brief summary of some of the chief results will here be given.