NOTICE TO THE READER. 



The present number, it will be observed, completes 

 the first volume of the Scientific Tracts. There was in 

 the early part of the volume, one number containing thir- 

 tysix pages. To complete the number of pages, as 

 was originally intended, we have made the two last 

 numbers shorter than the others. We have added 

 also a copious index of the subjects treated jn the vol- 

 ume. The miscellaneous character of the work renders 

 uch an index highly necessary. 



