POPULAR MISCELLANY 



573 



traverses an atmosphere containing a very 

 moderate quantity of dry coal dust, the 

 dusty atmosphere will explode with great 

 violence, and the explosion will continue and 

 pass throughout any length of such atmos- 

 phere, its violence and force increasing as it 

 progresses. The coal dust from several seams 

 in certain different districts is almost as sensi- 

 tive to explosion as gunpowder itself, the de- 

 gree of sensitiveness increasing in proportion 

 to its high quality and freedom from impuri- 

 ties. In mines which are briskly ventilated 

 there is a greater probability of explosion, 

 while in such cases it is generally more severe. 

 One of the most important results of the ex- 

 periments made has been to demonstrate that 

 certain high " explosives " (roburite, ammon- 

 ite, etc.) are incapable of igniting or explod- 

 ing coal dust. Mr. Hall, in face of these 

 facts, is therefore led to urge the total abo- 

 lition of gunpowder from coal mines for 

 blasting purposes and the substitution of 

 certain " high explosives " precautionary 

 measures which many large firms have al- 

 ready adopted. Apart from the danger of 

 using gunpowder arising from the ease with 

 which it starts a dust explosion, it appears 

 that in mere handling alone four hundred 

 lives have been sacrificed during the last 

 twenty years, while the loss of life from ex- 

 plosions caused by gunpowder during the same 

 time has been at least one half of the total loss 

 viz., 4,098 persons. With regard to pre- 

 ventive measures, every possible effort, it is 

 recommended, should be made, either by 

 watering the dry dust or removing it to 

 avoid accumulation, so that any accidental 

 ignition of fire damp may be limited in its 

 effects and prevented from developing into a 

 sweeping explosion through the agency of 

 dust. 



Birds of Michigan. The Bird Fauna of 

 Michigan, as described by Mr. A. J. Cook in 

 a bulletin of the State Agricultural Experi- 

 ment Station, being protected by the Great 

 Lakes nearly surrounding the State, is very 

 interesting. As is shown by Dr. C. Hai't 

 Merriam's colored map, it embraces rep- 

 resentatives of three distinct faunas viz., 

 the boreal in the north, which includes the 

 northern peninsula and the northern part 

 of the southern peninsula ; the transition, 

 which occupies nearly all the southern penin- 



sula, and reaches slightly into Indiana and 

 Ohio ; and the upper Souoran, which, though 

 mostly to the south of Michigan, reaches 

 into the southeastern and southwestern cor- 

 ners of the State. There are met in Michigan 

 many birds peculiar to the far north, and 

 others that dwell for the most part in the 

 States and countries to the south, even reach- 

 ing to and beyond the Gulf. The first are 

 illustrated in the Bohemian waxwing, the 

 spruce partridge, the Canada jay, and the 

 pine grosbeak ; and the summer redbird, the 

 mocking bird, and the cardinal redbird illus- 

 trate the second group. The large lakes at- 

 tract many birds that are usually maritime, 

 like the gulls and the terns ; while in south- 

 ern Michigan, with its prairies and wood- 

 lands, both widely distributed, are found the 

 prairie fauna, as illustrated in the pinnated 

 grouse, and those birds which are most at 

 home in the forests of Avooded areas, like 

 most of the thrushes and the warblers. 



The Future Work of the Americau Uni- 

 versity. Addressing the Pennsylvania State 

 Board of Agriculture on the Progress and 

 Practical Value of Agricultural Science, Dr. 

 Peter Collier gave a prominent place in 

 illustration to the work that has been done 

 in the analysis of fertilizers, whereby frauds 

 have been exposed, and farmers have been 

 pecuniarily benefited by the cheapening of 

 fertilizing materials and the assurance of 

 increased and improved crops. A further 

 illustration is found in the progress and prac- 

 tical applications of bacteriology a word 

 which, together with bacteria, does not oc- 

 cur in the standard dictionaries of 1868 

 by means of which the causes and cures of 

 the most serious maladies that affect crops 

 have been discovered and brought within the 

 reach of all, and such operations as the mak- 

 ing of butter and cheese are facilitated. One 

 would not have imagined a short time ago 

 that physics and physiology were the sisters 

 of psychology, or that ethics should consort 

 with economics and sociology in the same 

 laboratory, or that a professor of institu- 

 tional history should commend to his pupils 

 biology as a minor subject. Yet all these 

 things have really happened. Indeed, only 

 since Darwin and Spencer has it been pos- 

 sible to discover the essential kinship of the 

 various branches of knowledge. Projecting 



