the chimneys. (See Fig. 8.) This provides not only for the ventilation of sewer and house drain (the latter is rarely ventilated between the running trap and the sewer, though apt to be fouler than any portion of the public sewer), but it also causes each house drain to ventilate its proportion of the system, and prevents the usual concentration of the gases at a few points.

All ventilation being above the top of the house, there is very small chance of annoyance from smell, and so far as known there has been none noticed at any point save slightly at the perforated manholes at the foot of the trunk lines, and in three instances from "puffing" of fresh-air inlets to house drains-both of which were disconnected from the sewer and drain ventilation referred to.

Many of the houses at Nahant being provided with privies instead of water closets, and privies, too, of the poorest possible type, the annexed cut was adopted (see Fig. 9), as being perhaps more easily attended to than any other, and at the same time capable of being used, but not abused.

Any privy whose contents are received in a leaking vault, is undesirable, and when such vault is, as is not uncommonly the case, used as general slop-hopper as well, and the soil in the immediate neighborhood drenched periodically with the family filth, it should always be viewed with distrust.

At such points as seemed permissible, the option was given between the tub set on the slanting asphalt floor, as shown, or a thoroughly cemented shallow vault into which no slops were to be thrown.

The foregoing rather brief description with the accompanying plates may be sufficient to show what was done at Nahant, to prevent further soil pollution. In addition to this, and at the same time, an investigation was constantly going on, to ascertain the amount of both soil and water pollution already existing, the general condition of individual premises, inside and out, with a view to determining what remedial measures should be applied, how and when.

A slight knowledge of the local geology of the peninsula may be of service in this connection.

The soil at Nahant varies in character much more than is

generally supposed. Portions of the town show solid rock outcroppings; near by are deposits of fine white sand, fifty feet deep, or loose running gravel (drift) from twelve to thirty-five feet deep, and overlying the ledge, which still. shows distinctly the grooves and markings of former glacial action. A little further on is found stiff bluishgreen brick clay from twenty to sixty feet in depth, while the town gravel-pit at the west end exhibits a face of binding gravel of unusually good quality.

It being impossible to introduce public water on such short notice, the effort was made to remove all known sources of contamination, abolishing all cesspools and leaching vaults, draining marshes that smelled offensively, and, after removing all known causes of filth, to pump out and cleanse all wells and cisterns that afforded chemical or physical evidence of being tainted. There being hundreds of wells and cisterns used as drinking and cooking supplies, hundreds of chemical analyses were made, in the first instance to determine the general character of the water, and afterwards to ascertain what effect, if any, was produced (after removal of the supposed sources of trouble) by the pumping out and cleaning.

In many instances there was little or no improvement in the quality of the water, in others it was appreciably benefited, and occasionally, so far as could be ascertained chemically, waters were rendered entirely satisfactory, that were previously classed as decidedly injurious.

In the case of cistern water this might be expected in perhaps a majority of cases, and in a measure well water might show change for the better, though hardly to the extent indicated.

There being no public water during the season of 1882, most of the old wells and cisterns were of necessity depended upon for the major part of the drinking and cooking water, although many of the summer residents had spring water delivered periodically.

Of the wells and cisterns examined, nearly 60 per cent. contained water that was classed as undesirable (the proportion of wells and cisterns being about even).

Concisely speaking, there were 80 cases of typhoid fever