by virtue of a particular order to the director of the
douane, procured by the application of the English resident to the
French ministry. I am now preparing for my long journey; but, before I
leave this place, I shall send you the packet I mentioned, by Meriton.
Mean-while I must fulfil my promise in communicating the observations I
have had occasion to make upon this town and country.

The air of Boulogne is cold and moist, and, I believe, of consequence
unhealthy. Last winter the frost, which continued six weeks in London,
lasted here eight weeks without intermission; and the cold was so
intense, that, in the garden of the Capuchins, it split the bark of
several elms from top to bottom. On our arrival here we found all kinds
of fruit more backward than in England. The frost, in its progress to
Britain, is much weakened in crossing the sea. The atmosphere,
impregnated with saline particles, resists the operation of freezing.
Hence, in severe winters, all places near the sea-side are less cold
than more inland districts. This is the reason why the winter is often
more mild at Edinburgh than at London. A very great degree of cold is
required to freeze salt water. Indeed it will not freeze at all, until
it has deposited all its salt. It is now generally allowed among
philosophers, that water is no more than ice thawed by heat, either
solar, or subterranean, or both; and that this heat being expelled, it
would return to its natural consistence. This being the case, nothing
else is required for the freezing of water, than a certain degree of
cold, which may be generated by the help of salt, or spirit of nitre,
even under the line. I would propose, therefore, that an apparatus of
this sort should be provided in every ship that goes to sea; and in
case there should be a deficiency of fresh water on board, the seawater
may be rendered potable, by being first converted into ice.

The air of Boulogne is not only loaded with a great evaporation from
the sea, increased by strong gales of wind from the West and
South-West, which blow almost continually during the greatest part of
the year; but it is also subject to putrid vapours, arising from the
low marshy ground in the neighbourhood of the harbour, which is every
tide overflowed with seawater. This may be one cause of the scrofula
and rickets, which are two prevailing disorders among the children in
Boulogne. But I believe the former is more owing to the water used in
the Low