644 



POPULAR SCIENCE MONTHLY. 



The method pursued is as follows: The class is taken to a typical 

 place for illustrating the subject in hand. The area to be studied 

 is ])ointed out, and then for a half liour or so the class is asked 



to make observations unas- 

 sisted by the instructor and 

 with as little communication 

 among themselves as possi- 

 ble. Then they are called 

 together and questions are 

 asked to draw out the results 

 of their observations, free 

 discussion being invited at 

 this time, and questions from 

 the class answered by the in- 

 structor. Then the instruc- 

 tor explains the phenomena 

 studied, and finally gives a 

 general lecture upon the 

 particular subject involved. 

 Xotes, taken in the field, are 

 carried home and rewritten 

 and then handed in at the 

 next lesson, to be corrected 

 A printed synopsis is furnished each member 

 of the class at every lesson, for which payment is made sufficient 

 to cover the cost of the printing. Each member is also required 

 to be provided with a hammer, chisel, and compass. 



The course of instruction begins with a discussion of the gen- 

 eral principles of erosion, and one lesson each is given at places 

 illustrating an excess of chemical and mechanical action. At Med- 

 ford a very broad dike of coarsely crystalline diabase, penetrated 

 by numerous cracks, furnishes an exceptionally good opportunity 

 for the observation of rapid chemical decomposition, an almost 

 complete gradual transition being shown from the fresh unaltered 

 rock through all degrees of decomposition to the formation of soil. 

 The cause of the decomposition is exjjlained, with the resulting 

 products, and the history of the latter is traced till they form parts 

 or the whole of a new rock. A drumlin is seen, at Great Head, 

 Winthrop, being undermined and worn away by the waves. By 

 comparison with other drumlins in the neighborhood, the original 

 form of Great Head can be easily restored mentally and the effect 

 of waves and currents upon a coast can be readily appreciated. In 

 an excursion to North Adams and rides over the Hoosac Mountains 

 and to the summit of Greylock, rivers are seen in thoir various stages 



George H. Barton. 



and returned later. 



