cclviii GENERAL SUMMARY OF SCIENTIFIC AND 



line between Tarifa and Algesiras on the Spanish coast to 

 Ceuta and Tangier on the Morocco shore. The submarine 

 portion will be 44,100 feet, or nearly nine miles. This en- 

 terprise, thus far a mere proposition, will present far greater 

 difficulties to its completion than the similar project for tun- 

 neling the English Channel, although the latter, as project- 

 ed, will have more than twice the length of the former, in- 

 asmuch as the maximum depth of the Channel at the point 

 to be traversed does not exceed 180 feet, while that of the 

 Strait is 2G21 feet. A tunnel beneath the Strait would 

 therefore require to be bored at a much greater depth be- 

 neath the bed-rock say about 1000 feet which in turn 

 would demand entry and exit galleries each about three 

 miles in length. 



The following miscellaneous items have a general interest 

 in this department : The construction of a canal from Lake 

 Michigan to the Mississippi River has of late been strongly 

 advocated, as a means of lessening the cost of conveying the 

 produce of the Upper Mississippi Valley to the sea-boards. 

 The sum of 8000 florins has been voted by the States-Gener- 

 al of Holland for re-examining the project of draining the 

 Zuyder-Zee, and for soundings to determine the quality of 

 the soil at its bottom. A subterranean pneumatic postal 

 service is proposed between Paris and Versailles, in order 

 to facilitate communication between the seat of the govern- 

 ment at the latter, and the general service of the various 

 departments at the former place. The line proposed is a 

 double one, permitting the carriage of twenty kilos of dis- 

 patches an hour in both directions. The Mexican Congress 

 has lately granted an important concession, providing for 

 the construction of a railroad of the standard gauge (four 

 feet eight and a half inches) from the city of Leon, in the 

 state of Jalisco, to the Rio Bravo del Norte, there to con- 

 nect with the International Railway of Texas. The open- 

 ing of the Constantinople Underground Railway from Ga- 

 lata to Pera is worthy of mention. This unique \vork, 

 which was thrown open for traffic in January last, is 672 

 yards long, and conveys passengers from the level of the 

 Bosporus to the extreme height of Pera, an elevation of 

 200 feet, with an average gradient of one in ten. Its great- 

 est depth below the surface is eighty feet, and the motive- 



