238 



SCIENCE 



[N. S. Vol. XXXYIII. No. 972 



TEE IOWA ACADEMY OF SCIENCE 

 The twenty-seventh annual meeting of the acad 



emy was held in Alumni Hall, Iowa State College, 



Ames, beginning at 1:30 p.m., Friday, April 25, 

 President Pearson, of the Iowa State College, 



extended a welcome to the academy at 8:00 p.m. 



Friday. After this the public address on "Wealth 



from Worthlessness " was given by Dr. Thomas J. 



Burrill, professor emeritus of botany, University 



of Illinois. 



PROGRAM 



(Abstracts are by the authors) 

 Tramping about Puget Sound: T. H. MacBride. 

 Pure Lines and What they Mean to Iowa's Grain 

 Crop: L. C. Burnett. 



The Physiology of the Pollen of Trifolium pra- 

 tense: J. N. Martin. 



The Comparative Morplwlogy of the Legumes: 



J. N. Martin. 

 A Preliminary List of the Parasitic Fungi of 



Boone County, Iowa: H. S. Coe. 



A Partial List of the Parasitic Fungi of Decatwr 

 County, Iowa: J. P. Anderson. 



The Pollution of Underground Waters with Sew- 

 age through Fissures in Eochs: Henry AiBEET. 

 The possibility of pollution of underground 

 waters through fissures in rocks has long been a 

 well-established fact. The actual demonstration 

 of such as the source of eases or epidemics of 

 disease in Iowa has until recently not been proved. 

 The more superficial rocks of the state present 

 many joints or fissures. Although the epidemic 

 of typhoid fever in Cedar Falls during 1911 was 

 believed at that time to have occurred as a result 

 of the pollution of waters through fissures in 

 rocks, it is believed now that pollution occurred 

 through a wooden conduit which conducted the 

 water from the spring to the pumping station. 

 The best example that we have of an epidemic no 

 doubt traceable to pollution through fissures in. 

 rocks is the epidemic of typhoid fever which oc- 

 curred at Fort Dodge during the summer and fall 

 of 1912, during which about one hundred persons 

 were affected by the disease. The water supply of 

 Fort Dodge comes principally from the deep wells. 

 They also take the water from pipes beneath the 

 river. The source of infection was apparently 

 both from the pipes beneath the river and from 

 one of the deep wells. The feature of Interest is 

 in connection with the latter. This well (well No. 

 1), which was the first of the three wells as also 



the deepest one — being 1,827J feet deep and ex- 

 tending to the Jordan sandstone — was started at 

 the bottom of a large shaft which was constructed 

 several years previously for the purpose of sup- 

 plying the city with water. This shaft, which 

 measures 10 X 10 feet across, extends down for 

 90 feet. From the west side of the lower end of 

 this shaft a tunnel of 9 feet in diameter was 

 extended under the Des Moines River. This tun- 

 nel was driven in sandstone, so required but few 

 timbers for support, whereas the shaft has a 

 wooden casing for almost its entire extent. The 

 shaft extends successively from above downward 

 through the following layers of earth: 



Alluvial soil and clay 31 feet 



Limestone 6 feet 



Shale, blue 27 feet 



Limestone .' 6 feet 



Sandstone 42 feet* 



There are only about 20 feet of gravel, alluvial 

 soil and clay from the bottom of the river to the 

 first layer of limestone. Through this the water 

 from the river and surrounding soil will probably 

 pass quite readily and without efScient filtration. 

 It then comes to a layer of limestone which is 

 known to contain many fissures, through which 

 water may readily enter the shaft. Beneath the 

 limestone is a layer of blue shale, 27 feet in thick- 

 ness. This is relatively impermeable to water, 

 hence tends to keep the water from passing di- 

 rectly downward and so hastens the passage of 

 water laterally along the limestone fissures — in the 

 direction of least resistance — namely, toward the 

 shaft. Previous to the construction of the tunnel 

 the seepage into the shaft was at the rate of about 

 55 gallons per minute. This was increased to 80 

 gallons per minute by the construction of the 

 tunnel. This would seem to indicate that the 

 water which enters the shaft is of recent surface 

 origin. That the water must have come prin- 

 cipally through such fissures in the rocks is indi- 

 cated by the fact that when the shaft was con- 

 structed but little water appeared until after the 

 limestone layer with its fissures had been entered. 

 That the water which comes from the shaft is 

 polluted with sewage material has been shoim 

 repeatedly by clinical and bacteriological exam- 

 inations. When the first artesian well was drilled 

 (well No. 1) it was started from the bottom of 

 the above-mentioned shaft. The casing of this 

 well extends through the shaft and projects at the 



' Tunnel in this formation. 



