78 



SCIENCE, 



[Vol. IV., No. 77. 



When the announcements were made of the 

 honorary degrees conferred at the tercentenary 

 celebration of the University of Edinburgh, 

 some surprise was felt that American men of 

 science appeared to be forgotten, while Ameri- 

 can physicians and theologians were selected 

 with obvious discrimination for their academic 

 distinctions. It is now stated that the authori- 

 ties at Edinburgh intimated to several Ameri- 

 cans devoted to science, that the university 

 would confer upon them the degree of doctor 

 of laws if they would come and receive it, 

 and that, in case of their non-attendance this 

 year, they might be admitted to the honor if 

 present on some future occasion. The list of 

 men thus chosen may not be authentic, and we 

 shall therefore refrain from reprinting it ; but, 

 as given in the newspapers, it includes, among 

 others, a geologist and zoologist, a botanist, 

 an astronomer, and a philologist, every one of 

 whom would be acknowledged in this country 

 as a worthy representative of American science. 



There is fine opportunity to make the com- 

 ing electric exhibition in Philadelphia a public 

 educator as well as a brilliant display by giving 

 due care to the explanation of the different 

 groups of exhibits. Only a very small share 

 of the visitors to such exhibitions understand 

 what they see ; but by far the greater number 

 would gladly learn more than they know if the 

 way were open. The untaught majority of the 

 visitors may wonder and admire, but they really 

 learn very little. Their curiosity is excited, but 

 their reason is not satisfied. Printed explana- 

 tions are seldom given : verbal explanations are 

 often too technical to be of much value, even 

 when the exhibiters can be found, and are will- 

 ing to tell their story for the hundredth time. 



This might all be changed, if an extended 

 series of well-considered explanatory cards 

 were composed with the special object of 

 reaching the most elementary inquiry, and 

 arranged in such succession that the visitors 

 who follow around the aisles in proper order 

 should read a concise statement of the elements 

 essential to the various contrivances in the 



bewildering display. Take, for example, the 

 batteries, which will surely be exhibited in 

 large variet}- . At the beginning of this class 

 of exhibits, there should be a large card on 

 which should appear some such statement 

 as the following : ' ; The essential elements of 

 a battery are so and so ;. these essentials are 

 reached in various ways, thus and thus and 

 thus." Then in further explanation of the 

 different kinds of batteries, which should be 

 classified as rationally and as distinctly as 

 possible, the advantages claimed for each class 

 could be appropriately defined, as cheapness, 

 durability, intensity, constancy, etc. ; or the 

 special object in view might be stated, and the 

 peculiar means to this end briefly set forth. 



There would be a double gain accomplished 

 by such a method. The direct gain would be 

 a distinctly better understanding of the exhibi- 

 tion among the many intelligent visitors who 

 were not especially informed on electrical mat- 

 ters. The indirect gain would be a step in 

 general education, in the recognition of the 

 relation between the essentials of an apparatus 

 and the contrivances by which they are attained. 

 For most persons the contrivances are of small 

 importance : they cannot be remembered, ex- 

 cept in a few cases where peculiar reasons maj^ 

 give them special interest. But the essentials, 

 the principles of construction freed from the 

 details, are of the greatest service to all. The 

 time and work required for the preparation of 

 such guide-cards would be great, but the pub- 

 lic would consider them well expended. 



LETTERS TO THE EDITOR. 

 Cretaceous phosphates in Alabama. 



In a previous letter I announced the occurrence of 

 phosphates in the lower beds of the rotten limestone 

 of the cretaceous formation of Alabama. I have 

 since discovered that they are by no means confined 

 to this horizon. 



Immediately overlying the rotten limestone, and 

 forming the uppermost strata of the cretaceous for- 

 mation, are beds of marls and clays, alternating with 

 hard, crystalline, sandy limestones, usually assigned to 

 the Ripley group of Professor Hilgard. Specimens 

 examined from many localities show that these beds 

 in Alabama, from Livingston in Sumter county, east- 

 ward nearly to the Georgia line, are very generally 

 phosphatic. 



