On water supply / by Stevenson Macadam.

Date:
[1872?]
Catalogue details

Licence: Public Domain Mark

Credit: On water supply / by Stevenson Macadam. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    14/20 (page 338)
    for the city, the average of the whole waters may be obtained. This water has been collected at all seasons of the year, and the composition, as determined by chemical analysis, has been practically the same at all times. The Megget stream, which is the principal feeder of the loch, flows in on the north side with a deep channel, which, at a distance of 150 yards from the mouth of the stream is 90 feet deep, with a stony or pebbly bottom, as evidenced by the plumb striking hard upon it. Towards the east of the Meggfet the ground generally shallows near the side, which is caused by a delta being formed there, consisting of fine silt composed of the comminuted grayw^acke rock of the district, with some broken stalks of brackens, a little grass, and a few minute fragments of peat. These were the results of dredging, and also of the hollowed out lead plunger or plummet. On chemical examination of the silt when dried, not one per cent, consisted of organic matter. I have never seen cleaner silt dredged or taken from the bottom of any loch. In all the ponds and reservoirs in the Pentlands you have similar finely divided earthy matter, accompanied by a minute proportion of organic matter thrown down, the only difierences being that in the Pentland ponds the silt is more ferruginous and ochrey in its nature, and when agitated causes more discoloration of the water. At cer- tain parts, as at the north-west side of Glencorse reser- voir, where the burn from Loganlee enters, the silt contains a much larger proportion of organic matter, there being in some samples examined from 5 to 10 per cent. In lifting samples of water for chemical analysis, care should be taken that the water is collected as it naturally flows in the stream or loch, and that the banks or bottom be not disturbed. Where the water is to be taken from the side, it is better to lift it in a large spoon lined with porcelain and attached to a wooden pole, so that the operator may stand firmly on the bank without disturbing the stones or earth on the immediate brink, and be able to stretch out the instrument some feet into the stream or loch. Where no such lifter is used, and the collector stands on earth or stones immediately alongside, or in the water course, and