many parents might mistakenly have done, to divert him from this to a more "practical" line of pursuits, he fitted up for him a well-furnished chemical laboratory and workshop; and this laboratory was through all his life a favorite retreat of Carvill Lewis's, to which it was his delight to introduce his scientific friends. His interest in mineralogy and geology assumed a more definite and controlling shape when he was about twelve years old, when Dr. Isaac Lea gave him some specimens as the foundation of a collection, and stimulated him to go on studying them. A year later he and some playmates formed a scientific society, which continued in existence and of which he remained a member till 1875, when it disbanded. Having been graduated from the University of Pennsylvania in 1873 with the highest honors in the classical course, he took a post-graduate course of three years in the natural sciences. For several years after his graduation he divided his time almost equally between geology and astronomy. Twenty-nine communications by him are recorded in the "Proceedings of the Mineralogical and Geological Section of the Academy of Natural Sciences of Philadelphia," from 1877 to 1879. He gave to the American Association in 1877 a description of an aurora and of the zodiacal light as observed by him in May of that year, and notes by him on the zodiacal light were published in the "Proceedings of the American Association" and in the "American Journal of Science" in 1880. In 1879 he joined the Geological Survey of Pennsylvania as a volunteer member, and continued associated with it till 1884. In connection with this work he investigated the surface geology of the southern part of the State, and began the tracing of the great terminal glacial moraine with which his name is most closely associated, determining its course through the northern part of Pennsylvania. In all these researches, as well as his studies in mineralogy and petrology—notably in those relating to the diamond and to the archæan rocks—he was moved by an earnest spirit of independent inquiry, and afforded a living illustration of the force and application of his motto, "Truth for authority, not authority for truth." The controlling force of this principle in his life-work is emphasized in the simple record on his tombstone in Walmsley church-yard, Bolton, "He loved the truth."
In 1880 Mr. Lewis was elected Professor of Mineralogy in the Academy of Natural Sciences, Philadelphia; and in 1883, Professor of Geology in Haverford College. He held both of these positions at the time of his death. From 1885 to 1887 he was occupied during the Winters in petrologic studies in Heidelberg with Prof. Rosenbusch, and during the summers in field-work on the glacial geology [of England, Wales, Ireland, Switzerland, and northern Germany. The winter and spring of 1887-'88 were