the purposes of this work to say that, so far as Dr.
Salisbury's opinion is valuable, it is,--like the opinion of all other
writers on the subject,--fully in favor of perfect drainage as the one
great preventive of all malarial diseases.

_The evidence of the effect of drainage_ in removing the cause of malarial
diseases is complete and conclusive. Instances of such improvement in this
country are not rare, but they are much less numerous and less conspicuous
here than in England, where draining has been much more extensively
carried out, and where greater pains have been taken to collect testimony
as to its effects.

If there is any fact well established by satisfactory experience, it is
that thorough and judicious draining will entirely remove the local source
of the miasm which produces these diseases.

The voluminous reports of various Committees of the English Parliament,
appointed to investigate sanitary questions, are replete with information
concerning experience throughout the whole country, bearing directly on
this question.

Dr. Whitley, in his report to the Board of Health, (in 1864,) of an
extended tour of observation, says of one town that he examined:--

"Mr. Nicholls, who has been forty years in practice here, and whom I was
unable to see at the time of my visit, writes: Intermittent and remittent
are greatly on the decline since the improved state of drainage of the
town and surrounding district, and more particularly marked is this
alteration, since the introduction of the water-works in the place.
Although we have occasional outbreaks of intermittent and remittent, with
neuralgic attacks, they yield more speedily to remedies, and are not
attended by so much enlargement of the liver or spleen as formerly, and
dysentery is of rare occurrence."

Dr. Whitley sums up his case as follows:--

"It would appear from the foregoing inquiry, that intermittent and
remittent fevers, and their consequences, can no longer be regarded as
seriously affecting the health of the population, in many of the
districts, in which those diseases were formerly of a formidable
character. Thus, in Norfolk, Lincolnshire, and Cambridgeshire, counties in
which these diseases were both frequent and severe, all the evidence,
except that furnished by the Peterborough Infirmary, and, in a somewhat
less degree, in Spaulding, tends to show that they are at the present
time, comparatively rare and mild in form."

He mentions si