_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 deg. or a little above it,
but that the actual mean varies from 46 deg.-48 deg. on the Chiltern Hills to
48 deg.-50 deg. 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.

_Royston_ (London Road): lat. 52 deg. 2' 34'' N.; long. 0 deg. 1' 8'' W.; alt.
301 feet; observer, the late Ha