526 SALMON LEGISLA TION IN SCOTLAND. 



should be compelled to abstain from polluting any stream 

 so as to deteriorate it even slightly for primary purposes, 

 or render it injurious to fish life, and transgression of the 

 law should be visited with penalties so rigorous as to make 

 it their interest to avoid incurring them. 



The cost of purifying sewage must, of course, be borne 

 as a tax by the inhabitants of the town or district con- 

 cerned. In connection with this branch of the question, 

 there is an interesting paper printed in the Appendix to 

 the First Report of the Scottish Fisheries Improvement 

 Association, giving an account of the sewage purification 

 works at Hawick, from which it appears that the sewage both 

 from the town and the mills is so treated that the liquid 

 entering the river is perfectly innocuous to fish life when 

 mixed with nine-tenths of river water to one-tenth of 

 sewage, and the engineers state that the outflow from the 

 purification works during the day is about one-twentieth 

 of the minimum flow of the river, or one-fortieth of the 

 average summer flow, leaving floods out of account. The 

 cost to the ratepayers is from %d. to $d. per . When one 

 town can attain these results, there is no reason why all 

 should not do so. The same Report contains a short 

 account by the late Sir Robert Christison, of a method by 

 which paper or other manufacturers, instead of using and 

 polluting the large quantities of water which they do at 

 present, could effect their purposes quite as well by using 

 very small quantities, so that evaporation would be rendered 

 easy, and the residuum could be burnt up with the waste 

 heat of the works. 



The latest scientific testimony to the practicability of 

 purifying the discharges from mills and manufactories so 

 as to render them comparatively innocuous, is to be found 

 in a Report by Professor Crum Brown, of Edinburgh 



