58 



SCIENCE 



[N. S. Vol. XLII. No. 1071 



amount of material which would be accelerated 

 at the rate of one foot per second per second 

 by the gravity pull of the earth on a one-pound 

 body at 45° north latitude and at the level of 

 the sea. 



The word weight according to scientific 

 usage means the force with which the earth 

 pulls on a body, and it can be expressed most 

 intelligibly in dynes or poundals. 



Many teachers of engineering conform to 

 the popular usage in that they employ the word 

 weight to designate the absolutely definite and 

 invariant result which is obtained by weighing 

 a body on a balance scale, and to get what they 

 call the "mass" of the body they divide this 

 so-called weight by the acceleration of gravity 

 which is a variable! They do not remember, 

 as Professor Hoskins does, that they should 

 use the value of the acceleration of gravity at 

 a certain place which has been agreed upon, 

 and this is equivalent to saying that they do 

 not understand what they are doing when they 

 divide by " g." We wish indeed that the 

 thing were as simple as Professor Hoskins 

 thinks" it is, namely, a mere matter of dividing 

 by 32.1740 ; and of coarse it is just that simple 

 — to the man who understands it. 



W. S. Franklin, 

 Barry MaoNutt 



pre-wisconsesr glacial drift in the boston 



BASIN 



To THE Editor of Science : During the past 

 few weeks exposures have been made in con- 

 nection with extensive excavation work in the 

 city of Boston where one, and possibly two, 

 pre-Wisconsin drift sheets have been un- 

 covered. 



The evidence consists of a zone of extremely 

 weathered material beneath the Wisconsin 

 drift, an erosion unconformity, different types 

 of deposits, a slight trace of an interglacial 

 soil, some interglacial subsoils, and an appar- 

 ent difference in direction of the source of 

 included debris. It was possible to determine 

 with some accuracy the zone of post-Wiscon- 

 sin oxidation, and the final shaping of the 



6 See footnote on page 685, Science, May 7, 

 1915. 



ridge in which this evidence was found ap- 

 pears to be due to the re-advance of an ice 

 sheet which slightly contorted the uppermost 

 waterlain materials. The axis of this ridge is 

 accordant with the direction of the striaa of 

 the last glacial advance in the region. 



A paper is now in preparation covering in 

 more detail this important clue to older Pleis- 

 tocene deposits in eastern Massachusetts. 



E. Preston Wentworth 



Haevakd Univeesitt 



a serious new wheat rust in this country 

 On May 21 of this year, a party represent- 

 ing the office of cereal investigations of the 

 U. S. Bureau of Plant Industry discovered 

 the yellow leaf rust (Puccinia glumarum 

 Eriks. and Henn.) of wheat on several vari- 

 eties of wheat in a field in the vicinity of the 

 Indian school at Saeaton, Ariz. The pres- 

 ence of the rust was first called to the atten- 

 tion of the party by Dr. F. K0lpin Ravn, of 

 Copenhagen, Denmark, temporarily employed 

 by the U. S. Department of Agriculture in 

 consultation with officials of the department 

 on cereal diseases. At about the same time, 

 A. G. Johnson found the rust also on Hordeum 

 murinum in southern California. The rust 

 was not afterwards found on wheat anywhere 

 in California, but later, during June, was 

 found in considerable abundance at various 

 places in Oregon and Washington, and to 

 some extent in Idaho, and a very few speci- 

 mens at Bozeman, Mont., and Logan, Utah. 

 Up to July 1 it has not been seen anywhere 

 east of the Rocky Mountains. In Oregon and 

 Washington the rust was also found on barley, 

 and at PuUman, Wash., it was found by the 

 writer on a species of wild grass as yet un- 

 identified. 



In various minor ways Dr. Ravn has been 

 of great help to the cereal pathologists, but the 

 discovery of the presence of this rust is a par- 

 ticularly interesting example of the benefit re- 

 sulting from a cooperation of foreign botanists 

 occasionally in the investigation of problems 

 in this country with which such men are al- 

 ready acquainted in their own country. This 

 rust being common in Europe and usually the 



