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THE POPULAR SCIENCE MONTHLY. 



hausted at the bottom, in reversal of the 

 ordinary process, and under this condition 

 it does not produce the draft or cause the 

 sudden cooling that are so objectionable 

 under the usual method of ventilation. 



Work of the United States Fish Commis- 

 sion, In the work of the United States Com- 

 mission of Fish and Fisheries, the summer 

 of 1890 was spent by the steamer Albatross 

 in Bering Sea, where the principal banks 

 frequented by the cod were surveyed. The 

 season was too short to complete the work, 

 and it will have to be resumed at some fu- 

 ture time. The position of the western mar- 

 gin of the continental platform was, how- 

 ever, defined for a considerable distance, 

 and a good beginning was made toward a 

 knowledge of those physical and biological 

 features of the sea which relate to the habits 

 and distribution of the fur seal and other 

 aquatic mammals. By the surveys of the 

 coasts of Washington, Oregon, and Califor- 

 nia, the contour of the continental border 

 has been developed from the shore line into 

 depths of two hundred fathoms as far south 

 as Point Conception, while the region be- 

 tween that place and San Diego had been 

 previously explored. Temperature, density, 

 and biological observations in different parts 

 of San Francisco Bay indicate that the waters 

 of that region are not, as has hitherto been 

 supposed, unsuited to the breeding of Atlan- 

 tic coast oysters. A scientific investigation 

 was made with the Albatross during the 

 early part of 1891, under the direction of 

 Prof. Alexander Agassiz, of the waters ly- 

 ing off the western coast of America between 

 Cape San Francisco and the Galapagos Is- 

 lands on the south and the Gulf of Califor- 

 nia on the north. The most extensive and 

 important operations on the Atlantic coast 

 were conducted in the interest of the oyster 

 industry, in the coast waters of South Caro- 

 lina and Maryland and Virginia, and in Long 

 Island Sound. Dr. Bashf ord Dean, of Colum- 

 bia College, was commissioned to study the 

 methods of oyster culture practiced in Euro- 

 pean countries and to prepare a series of 

 illustrated reports concerning them. The 

 physical inquiries in the mackerel region off 

 the southern New England coast, under the 

 direction of Prof. William Libby, Jr., were 

 continued in 1889 and 1890 ; and the investi- 



gations respecting the interior waters of the 

 country were conducted in twelve States and 

 Territories on an extensive scale and with 

 important practical results. The work of 

 the Division of Fish Culture was continued 

 at twenty-two stations in fifteen States. 



The Theory of Special Assessments, 



According to the study of this subject made 

 by Victor Rosewater (Columbia College Se- 

 ries), the underlying principle of special 

 assessment for benefit first appeared in this 

 country in the provisions of a provincial law 

 of New York in the year 1691. The effect- 

 ive clause of this statute was copied from 

 an English act passed in 1667, and re-enact- 

 ed in 1670, to regulate the rebuilding of 

 London after the great fire. Thus the idea 

 was not, as some have supposed, a native 

 American one, but the substance of the 

 plan had been put into English books twenty 

 years before. The New York law remained 

 unrepealed, but inoperative, till 1787, when 

 it was adapted more closely to existing ne- 

 cessities. This method of raising revenue 

 for local improvements remained for a long 

 time peculiar to New York. It did not be- 

 gin to extend to the other commonwealths 

 till after the people had begun to recover 

 from the effects of the War of 1812. The 

 first development of the system, therefore, 

 corresponds roughly with the movements for 

 the construction of internal improvements 

 covering the years just before and after 

 1830, and dying out with the crisis of 1837. 

 The era of premature railway building about 

 1850 witnessed another movement of the 

 kind in the newer States and Territories. 

 The last movement, begun immediately after 

 the close of the civil war, was more general 

 than the others ; has not yet wholly ceased ; 

 and has passed over into Toronto, Canada. 

 The justification of the policy of special as- 

 sessments is to be found in the principle that 

 where an expense is to be incurred by a local 

 authority which results in special, distinct, 

 and measurable advantages to the property 

 of particular persons, it is more equitable that 

 those who benefit thereby should contribute 

 to the expense to the extent of those benefits 

 than that the burden should be placed upon 

 others who have received no such special ad- 

 vantages. Among other methods of recover- 

 ing the expense of improvements, besides 



