Mud walls are inexpensive. The price paid for the walls of the above cottage was 5s. per perch, i.e. a piece of wall 1 foot high, 15 inches thick, and 16 feet long.

The Model By-Laws of the Local Government Board say that the walls of a dwelling-house must be of hard and incombustible material bonded together with good mortar or cement. Now as mud is not hard, contains straw, and is not bonded with anything, it is doubtfully by-legal in districts which have adopted these Model By-laws. In the late fire at Andover it was found that while the thatched roofs blazed, the old mud walls of the cottages withstood the fury of the flames. When the tendency of by-laws is to boycott a local building material and to extinguish a local industry, the pros and cons ought to be very carefully considered.

An interesting feature of this cottage is the rainwater tank. Although I have a deep well close at hand which supplies an abundance of pure water, I was anxious to ascertain how far rain-water falling on the roof was capable of being utilised for household purposes, notwithstanding that in some districts of England cottages which are dependent upon rain-water only are not permitted. With this end in view, I was careful to provide a very plain, simple roof, without recesses for the lodgment of dirt or nests, and it was this which led me to use slates as a roofing material in preference to the more picturesque tiles which grow moss. My rainwater tank is constructed on the principle of the Venetian cistern. In a city which reached the highest pinnacles of commercial and artistic supremacy on rain-water,' one is tolerably sure to get valuable ideas for the collection and storage of that commodity. The Venetian cistern is of large capacity, and is so arranged that all water drawn from the central well has previously passed

through a sand filter. The tank is circular in form, having an internal diameter of 7 feet and a depth of 10 feet. It is divided down the centre by a diaphragm, which is perforated at the bottom by three agricultural drain pipes. Each half of the tank contains 3 feet of filtering material consisting of (from above, down) 1 foot of coarse gravel, 1 foot of fine gravel, and 1 foot of sand. The rain-water which falls from the roof passes through two strainers contained in an ornamental vase, and then, before being pumped, passes down through 1 foot of coarse gravel, 1 foot of fine gravel, and 1 foot of sand, and up through a similar filter, before it can be drawn from the pump. The tank is constructed entirely of cement concrete, and the pump has a copper suction pipe. It was important to avoid the use of lead, iron, or galvanised iron for the storage of rain-water intended for dietetic purposes. It will be noticed that all the water has to be raised by a pump, so that none of it can accidentally run to waste. The drips from the pump are conducted back into the unfiltered half, and should a boy play with the pump, he will merely ensure a double filtration for the water, and will not be able to waste any of it. I believe that half the water which we are supposed to 'use' is merely wasted by carelessness and bad taps. It will be noted that the water tank has been brought to the front of the house, and that an ornamental vase has been used for conducting the water from the roof. Anything amiss with the water tank will be noticed at once. This seems better than a dirty water-butt in an obscure corner. Those who have more money and taste will, I hope, soon outdo me in this direction. I commend the rain-water tank to the attention of architects.

It may be well to dwell for a moment on the powers of this roof as a rain collector. The area of the roof is