20. Workmanship. - To ensure sound sanitary work, the best skilled labour must be employed under the supervision of a competent expert, and all completed work must be carefully and adequately tested before being passed.

These conditions will apply to the design of every system of drainage, from the cottage to the mansion, in a greater or less degree, according to the requirements of each, dependent upon the number and nature of the sanitary appliances in use for carrying off the foul water, etc. In the cottage, the only internal sanitary appliance is the kitchen sink, and to design a scheme of drainage to carry away the foul water from this, as well as the rain-water from the roof and back-yard, is not a very difficult matter, so long as the cottages are built singly or in pairs.

When, however, we have to deal with houses in rows, certain difficulties present themselves, difficulties not requiring any special engineering to overcome, for they arise solely from recent judicial interpretations of the words "drain" and ••sewer", as defined by Sec. 4 of the Public Health Act, 1875. To the ordinary mind, it has hitherto been always understood that those pipes which are within the premises belonging to the house, such as the yard or garden and the passage common to several houses, whether built in rows or otherwise, and which have been cleansed and maintained by the owners, were drains, as distinguished from the sewer in the adjacent street or road, which conveys the sewage from the several houses on either ride.

Ml these long-established notions have been swept away by the decision, in the Halifax case of Travis v. Uttley (Court of Appeal, Nov. 27, Dec. 4, 1893, -vide Law Reports, 1894, I. Q. B. D., p. 233); though there have been several cases since that date, the decision remained unchanged until the summer of 1897, when in the Queen's Bench Division, before Justices Cave and Ridley, the case of Seal v. Merthyr-Tidfil Urban Dietrid Council was heard, when, after reviewing all the facts relating to the case, Mr. Justive Caw, in summing up. said, "What is a ' private drain' within the meaning of this Section? It appears to me to apply to a drain constructed on private premises to which the public have not access. "Private' is to be taken in that sense; that is, as being a drain which is private, and constructed on private land, - on land which is not open to the public." This further decision, together with the different interpretation of the word "drain" in the Public Health Act, 1890 (which is an adoptive act), renders the whole position most confusing and unsatisfactory.

According to the Public Health Act, 1875, a "sewer" is a drain " into which the drainage of two or more buildings or premises occupied by different persons is conveyed". Thus, in Fig. 307, which represents the drains from the backs of four houses communicating with a 9-inch pipe, this pipe is, according to the definition, a "drain" from a to the junction of the branch-drain from B, while beyond this point it is a "sewer". The subject will be further discussed by Dr. A. Wynter Blyth, who is a barrister as well as a doctor, in the Section on "Sanitary Law", and for additional information reference may be made to tin-very excellent paper, read before the Sanitary Institute, on "Combined Drainage", by J. F. J. Sykes, M.D., D.Sc., and W. N. Blair, Assoe. M. Inst. C.E. (vide Vol. XVI., Part II., Journal of Sanitary Instifntr. p. 274), and also a paper read by Mr. R. Godfrey, Assoc. M. Inst. C.E.,before the Association of Municipal and County Engineers (vide Proceedings, Vol XXI. p. 75).

Apart from the legal difficulties caused by carrying the main drain through the back-yards, as shown in the diagram, there are others, which may and do occur, caused by what we may call economical promptings. Taking again the block abcd, the proper position for the main drain is in the passage as shown by double lines, the branch drain from each sink being carried through the yard belonging to each house; but some builders, with a desire to save the cost of repeating the portion of the branch drain marked x x, lay the main in tin position shown by the double dotted lines, and the branches passing from one yard through the next. If, at any time after the houses are built, any one of them should be sold, the viciousness of this system of drain-planning would present itself, should there be any stoppage in the drain. Suppose the house D to have been sold separately, and that a stoppage occurs at the junction of the branch from C; this being upon the premises of D, 0 has no right of entry to repair, and should D be unwilling to assent to such entry, not only would C be inconvenienced by the stoppage, but A and b also, who might too be different owners. Such difficulties as are here presented are swept away by the Halifax case, so far as relates to D and C, but if the decision in the Merthyr case is the correct one, then they will remain. It is an excellent rule in all circumstances to keep the drains required for any house solely within the premises belonging to that house, until the public street or passage is reached The plans in Plate XIV. show a well-arranged house having all the necessary sanitary appliances, and it is our purpose to design a system of drains that will carry away all the sewage, waste water, and rain-water, not only in such a manner as will comply with the conditions already laid down, but that will also onomical in construction. Many systems, while doing their work satisfactorily, are complicated by an excessive number of unnecessary drains, and have been costly to construct by reason of the routes chosen, or from the depths at which the drains have been laid. In the designing of the position for the various sanitary appliances, their concentration should be aimed at so as to reduce the number of branch drains as far as possible consistent with efficiency.

Fig. 307.   Diagram Illustrating the terms Sewer and Drain.