P OP ULAR MIS CELL ANY. 



715 



way a thick mass of intermingled soil and 

 silk was formed. The only effort at nest- 

 building which it made was a rude burrow 

 against the side of the box. This burrow 

 was entirely destitute of silken lining, al- 

 though occasionally the opening would be 

 overspun with a thin sheet. 



Origin of Archaan Graphite. — In a paper 

 at the British Association on the origin of 

 graphite in the archaean rocks, the Rev. A. 

 Irving points out that the occurrence of car- 

 bon in late rocks as the result of plant-life 

 is no argument to prove that the graphite of 

 the archaean is of similar origin. Indeed, 

 conditions were then so diiferent that this 

 mode of origin is extremely unlikely. Ele- 

 mentary carbon is produced in three ways : 

 in pig-iron, by reduction of carbonic acid by 

 alkali metals, and by contact action of heated 

 surfaces on hydrocarbons. As hydrocarbons 

 exist in the heads of comets, some method 

 of origin like the last is far more probable 

 than that the graphite should be phytogenic. 

 The author thought that Mobius's investiga- 

 tions disproved the organic origin of eozoon ; 

 the iron oxides of the American archaean 

 would come from the combustion of iron 

 vapor in oxygen, while the unfossiliferous 

 limestones of the archaean can be explained 

 on purely chemical and physical principles. 



The Country Schools of New York.— The 

 State Superintendent of Pubhc Instruction 

 of New York, in his last report, draws an 

 unpleasant picture of the condition of the 

 rural schools. In them, he says, " the work 

 done depends almost exclusively upon the 

 character and capability of the teacher. 

 There is no ' system ' to fall back upon, no 

 machine which will turn out passable work, 

 whether or no. If the teacher is discerning 

 and bright and enthusiastic, results will 

 frequently be attained which surpass any 

 accomplished in the great schools ; if in- 

 different, the results are of no consequence. 

 . . . All teachers are entitled to considera- 

 tion, for their work is trying and exacting ; 

 but this is more strikingly so in the cross- 

 roads districts than elsewhere. Their pay 

 is small. . . . Their work is not confined to 

 a single grade ; they must meet the require- 

 ments of all grades and all classes. They 

 must lay out their own course of study, if 



they have any. Text-books are frequently an- 

 tiquated ; there is no uniformity, even in the 

 same school, and frequently not in the same 

 class, and the teacher finds it impossible to 

 work improvement. The school is very 

 likely maintained only twenty-eight weeks in 

 the year, just long enough to share in the 

 public moneys. Attendance is irregular. 

 Trustees drive hard bargains, for the num. 

 ber of young persons who want the place is 

 very large. Continual change in the teach- 

 ers is the order of the day. The time of 

 employment is but for a single term, and 

 frequently the trustee undertakes to make it 

 by the day or the week, in order that he may 

 be free to effect a change at any time, or 

 that he may withhold pay, in violation of 

 the spirit and intent of the statute, for the 

 week occupied in attendance upon a teach- 

 ers' institute. Supervision amounts to little 

 or nothing, for distances are great, during a 

 good part of the year roads are impassable, 

 and it is physically impossible for the com- 

 missioner, with generally more than one 

 hundred schools under his charge, to visit 

 each very frequently." 



The Energy in an Earthquake.— After 



explaining, in the American Association, 

 the impossibility of calculating the intensity 

 of an earthquake more than approximately, 

 Prof. T. C. Mendcnhall applied a formula 

 to determine the energy involved in the Jap- 

 anese earthquake of January 15, 188V, which 

 disturbed over 30,000 square miles of terri- 

 tory. He said : " Assuming a mass of 150 

 pounds per cubic feet, and taking a cubic 

 mile as the volume to be considered, I find 

 that to put it in vibration required the ex- 

 penditure of 2,500,000,000 pounds of energy. 

 Assuming an area of 100 miles square, with 

 a mean depth of one mile, was thus in vibra- 

 tion at any one instant of time — which is not 

 improbable, considering the known rate of 

 transmission and the long duration of the 

 earthquake — the amount of energy thus rep- 

 resented would be 25 X 10-12 foot-pounds. 

 This energy might be generated by the fall, 

 under the action of gravity, of a cube of rock 

 1,000 feet on each edge, the mass of which 

 would be 75,000,000 tons, through a verti- 

 cal distance of 166 feet." Also, assuming 

 certain magnitudes, " I find the energy of 

 a cubic mile of the Charleston earthquake, 



