178 POPULAR SCIENCE MONTHLY. 



De Varona, Engineer of Water Supply, with the writer in immediate 

 charge. 



The filtration of all surface water used for domestic supply is one 

 of the probabilities of the future. For years many of the large cities of 

 Europe have been supplied with filtered water, and in England alone 

 more than ten million people are using water from which all danger 

 from disease germs has been removed. In x\merica filtration has gained 

 ground but slowly, and in some of our cities the condition of the drink- 

 ing-water is a disgrace to civilization. A German health officer once said 

 to me: 'You Americans are a queer people; you filter sewage, but you 

 drink water raw.' One reason for our tardiness in following the practice 

 of the Old World is the fact that the conditions here are not in all re- 

 spects the same as in Europe. The old methods of filtration cannot be 

 successfully applied to many of our American waters, and water-works' 

 engineers have felt that before expensive works were undertaken the 

 problems should be carefully studied by direct experiment with respect 

 to existing conditions. Thus, recent years have witnessed the operation 

 of experimental filter plants unequalled in magnitude, in the scope of 

 their work and in the accuracy of their methods of investigation. 



The experiment station of the Massachusetts State Board of Health 

 at Lawrence was started in 1897 and is still in operation. The results 

 of the investigations of the principles involved in the purification of 

 water and sewage by sand filtration have become classic in the annals 

 of sanitary engineering, and the annual reports are still furnishing 

 results of the highest scientific value. At the present time the work 

 is in charge of Mr. H. W. Clark, Chemist of the Board. One practical 

 result of these experiments was the construction of a sand filter of novel 

 type for the purification of the water supply of the city of Eaw fence, 

 and the immediate reduction of the typhoid fever rate showed the suc- 

 cess of the undertaking. The water of the Merrimac River, at Law- 

 rence, though polluted, is comparatively clear, and it became evident 

 that methods of filtration that were applicable to water of this character 

 would not be necessarily successful where the water was highly colored 

 and turbid. Experiments were, therefore, begun in other cities. 



In Boston, where the water was of higher color than at Lawrence, 

 and where microscopic organisms were sometimes numerous, a filtration 

 station was in operation from 1892 to 1895. Six sand filters, each with 

 .in area, of one-thousandth of an acre, and a large number of smaller 

 filters, were used under varying conditions. The station was in charge 

 of Mr. Win. E. Foss, under the direction of Mr. Desmond Fitzgerald, 

 C. E. The analytical work was done partly at the Massachusetts Insti- 

 tute of Technology and partly at the Biological Laboratory described 

 above. It is much to be regretted that the results of these experiments 

 \ere never published. 



