62 



PROCEEDINGS OF THE AMHERST MEETING 



faulted is seen. The model is also useful in demonstrating horizontal 

 faulting, such as that which produced the San Franciscan earthquake, 

 and can also be used to show hinge faults. 



4. A piece of apparatus designed by AVoodworth and Fore to show the 

 principle on which the seismograph works and to demonstrate earth tilts 

 was at one time on sale, but, as far as known, can not now be purchased. 

 As students in elementary geology have difficulty in understanding, with- 

 out a visual demonstration, how earthquake shocks are recorded on instru- 

 ments, something of this sort should be made available. 



Figure 4. — Model which shows Slip, Dip-slip, Strike-slip, Net-shift, and Drag-dip 



5. JaggarV geyser experiment is one which has been found both inter- 

 esting and useful. Snow's apparatus, as illustrated -and described by 

 Hobbs, 5 is simpler and possibly better on that account and has been used 

 for ten or more years. 



6. Leith and Mead's netting model, designed to show non-rotational 

 and rotational strains and shear, is simple and inexpensive and useful in 

 advanced courses. 



7. A piece of apparatus to show the path of a bundle of light rays re- 

 jected from a mirror and passing through a lower nicol prism, mineral 

 section, and upper nicol in crossed position has been designed by Prof. 

 F. Bascom and has proved very serviceable in petrography. No dealer 

 has this for sale. 



*T. A. Jaggar : Journal of Science, 4th series, vol. 5, 189S, pp. 323-333. Snow's ap- 

 paratus is illustrated in Hobbs' "Earth features," p. 193. 

 5 Leith : Structural Geology, pp. 18-21. 



