POPULAR MISCELLANY. 



283 



Ohio, Indiana, the greater part of Michigan, 

 Northern Illinois, Eastern and Northern Wis- 

 consin, Northern Minnesota, North-Central 

 Iowa, Eastern Dakota, and many parts of 

 Canada. Of valley drift, attention was di- 

 rected to the moraine-headed valley trains, 

 and the loess tracts. The former show 

 progressively coarser material toward their 

 origin, and merge into expanded heads, 

 blending with the moraines in which they 

 begin. The broad tracts of fine silt, desig- 

 nated " loess," occupy the Mississippi up to 

 East-Central Minnesota, the Missouri up to 

 Southern Dakota, the Illinois and Wabash 

 up to their great bends, and the Ohio up to 

 Southeastern Indiana. Two other assorted 

 deposits considered were those overspread- 

 ing the great basin of the St. Lawrence 

 and the Winnipeg basin. These often pre- 

 sent, among their surest credentials, over- 

 flow channels to the southward, crossing 

 divides sometimes hundreds of feet above 

 existing outlets, and varying in altitude 

 among themselves at least two thousand 

 feet. 



Durability of Water-Color Drawings. — 



A controversy, which recently arose in Eng- 

 land on the durability of water-color draw- 

 ings, led to an exhibition of pictures at which 

 visitors were given opportunity to test for 

 themselves the capacity of the specimens 

 shown to hold their colors. The " Satur- 

 day Review " draws from the average of the 

 works the conclusions that, in pictures or 

 passages of especially vivid color, little in 

 the way of fading need be apprehended ; 

 but, in the delicate, broad, and thin washes 

 of the landscape-painter, " changes of va- 

 rious kinds are apt to take place, capri- 

 ciously, as it would seem, and from various 

 causes, of which long and continued expos- 

 ure to light is probably one. Pending more 

 accurate experiments, collectors and mana- 

 gers of public institutions will do well to 

 keep their framed drawings rigorously pro- 

 tected from pure sunlight, and not exposed 

 more constantly than is necessary to ordinary 

 daylight ; for which purpose they should be 

 covered with blinds or curtains during the 

 long hours of the summer mornings, and 

 generally when the rooms in which they are 

 hung are disused. Also it will probably be 

 well to vary from time to time the drawings 



exhibited, and to return each occasionally 

 for a period of rest to the drawer or cabi- 

 net. But on the question of frames versus 

 portfolios, it has to be remembered that a 

 well-framed drawing is secure at least from 

 effects of atmosphere ; while in portfolios 

 it is only by extreme and constant care that 

 risks can be avoided from dust and rub- 

 bing." 



Marine Signals. — Sir James Douglass 

 addressed the Section of Mechanical Sci- 

 ence of the British Association on light- 

 houses and marine signals. There are at 

 present not less than eighty-six distinctive 

 characters in use throughout the light- 

 houses and light-vessels of the world ; and 

 as their numbers increase so does the ne- 

 cessity for giving a more clearly distinctive 

 character to each light over certain defi- 

 nite ranges of coast. This important ques- 

 tion of affording to each light complete dis- 

 tinctive individuality is receiving the atten- 

 tion of lighthouse authorities at home and 

 abroad, and it is hoped that greater uni- 

 formity and consequent benefit to the mari- 

 ner will result. There are now about seven 

 hundred fog-signals, of various descriptions, 

 on the coasts of the world ; and their con- 

 struction and operation have been the sub- 

 ject of careful experiment and scientific re- 

 search. Unfortunately, the results thus far 

 have not been so satisfactory as could be 

 desired. This is owing partly to the very 

 short range of the most powerful of the 

 signals under occasional unfavorable con- 

 ditions of the atmosphere during fog, and 

 partly to the present want of reliable tests 

 for enabling the mariner to determine at 

 any time how far the atmospheric condi- 

 tions are against him in listening for the 

 signal. The question of utilizing lighthouses 

 and light-vessels as signal-stations in tele- 

 graphic communication with each other and 

 with a central station, has received the con- 

 sideration of lighthouse authorities gener- 

 ally, and has been made of practical effect 

 in Canada. Buoys are illuminated with com- 

 pressed oil-gas ; and automatic lighting ap- 

 paratus has been applied to those in occa- 

 sionally inaccessible positions. A compar- 

 ative test of the merits of electricity, gas, 

 and mineral oil, as lighthouse illuminants, 

 carried on for twelve months, has given the 



