November 7, 1884.] 



SCIENCE. 



443 



SHAFT-SINKING BY FREEZING. 



The method of shaft- sinking recently invented by 

 Mr. F. H. Poetsch of Aschersleben, by means of the 

 artificial production of low temperatures, is an illus- 

 tration of the new and unexpected directions in 

 which chemical and physical processes become of 

 use. In sinking shafts for mining and other engi- 

 neering purposes, and in the construction of deep 

 foundations, the presence of quicksand has always 

 been dreaded; for it can be penetrated, if at all, only 

 with great difficulty and expense. While the use of 

 compressed air has enabled us to sink shafts and place 

 foundations in water-bearing strata, we are limited 

 to depths not much exceeding one hundred feet by 

 the practical inability of the human system to en- 

 dure greater air-pressures. Mr. Poetsch has success- 

 fully applied to such cases a method of shaft-sinking 

 by freezing, which bids fair to remove all the trouble. 

 He proposes to do away with the pumps and air- 

 compressors, to transform the surrounding liquid soil 

 into a solid wall of ice, and in this way to reduce the 

 problem of shaft-sinking to that of work in hard, dry 

 ground. 



A system of tubes is sunk around and within the 

 site of the proposed shaft, and a saline solution such 

 as chloride of calcium, of very low temperature, 

 having for its freezing-point — 40° F., and passed 

 through a Carre ice-machine, is caused to circulate 

 through the system by means of inner tubes until 

 the semi-fluid soil is solidified by congelation. The 

 temperature of the ground has been reduced, in actu- 

 al work, from 52° F. to 0° F. in twenty days, freez- 

 ing within a circle of about five feet diameter around 

 each pipe, and producing in the quicksand the solidi- 

 ty of sandstone, with all its properties of stability, 

 and a conchoidal fracture. 



The method of putting in place the freezing-pipes 

 varies with the locality. When the quicksand has a 

 slight thickness only, and the shaft is already sunk 

 to the water-level, the pipes are simply forced into 

 the sand with a sand-pump working inside. This was 

 the system actually employed at the Archibald mine, 

 near Schneidlingen, Prussia, where twenty-three 

 pipes nearly eight inches in diameter were sunk 

 through a water-bearing stratum eighteen feet thick, 

 and at the Max mine, near Michalkowitz, Upper Si- 

 lesia. In other cases a boring-machine is used which 

 puts down four pipes at a time, and is worked by the 

 water-jet system. If the fluid soil lies at no great 

 depth, the holes for the pipes are bored from the sur- 

 face, and the pipes are so arranged that the shaft can 

 be sunk inside of them ; but, when the water-stra- 

 tum is at a great depth below the surface, a shaft of 

 some three feet greater diameter than the finished 

 shaft is first sunk through the firm ground, so as to 

 permit of the sinking of the pipes through the fluid 

 stratum, and the construction of the final shaft within 

 them. 



At the Centrum mine, near Berlin, one hundred 

 and seven feet of quicksand had to be penetrated. 

 Engineers had been baffled for years in their attempts 

 to overcome the difficulties. In thirty-three days, 



with sixteen pipes, Mr. Poetsch had secured a wall of 

 ice six feet thick around the shaft area, and the shaft 

 is now being excavated and curbed without special 

 difficulty. 



A series of bridge-piers is to be sunk by this method 

 near Bucharest, Austria. This last contract has espe- 

 cial interest; as it will afford a test of the seemingly 

 just claim of the inventor, that his plan opens up 

 great possibilities in founding bridge-piers. As op- 

 posed to the compressed-air process, the main advan- 

 tages are in the practical absence of limitation in 

 depth, and the relief of the laborers from the effects 

 of severe air-pressures. The entire plant can be used 

 repeatedly, as the pipes can be withdrawn as soon as 

 the ground thaws out. The cost of an undertaking 

 can also be estimated in advance with reasonable 

 certainty. 



A more detailed description of this process is given 

 in the Engineering news, June 7, 1884, based on an 

 article from the Zeitschrift fiir berg., hutlen., und 

 salinenwesen in Preussischen stadte, and in the Engi- 

 neering news, July 5, 1884, with illustrations of the 

 plant used at the Centrum mine. 



Chas. E. Greene. 



AMERICAN ORIENTAL SOCIETY. 



The American oriental society held its autumn 

 meeting at the Johns Hopkins university in Balti- 

 more on Wednesday and Thursday, Oct. 29 and 30. 

 A grammar of the Siamese language was reported 

 as nearly finished by one of the members, Kev. S. C. 

 George. A vocabulary of the Mortlock dialect had 

 been offered to the society for publication by a mis- 

 sionary in the Caroline Islands, and a translation of 

 the Prem Sagar from the original Hindi by the Rev. 

 J. M. Jamieson. The Peking missionary association 

 sent resolutions respecting the eminent Sinologue, 

 Dr. S. W. Williams, the lately deceased president of 

 the Oriental society. 



Fourteen papers were presented to the society. 

 The extreme east was represented by a paper on the 

 Korean numerals and alphabet. Mr. Bockhill, an 

 attache of the U. S. embassy to China, presented to 

 the library a Tibetan book of poems by Milaraspa, a 

 Buddhist missionary of the eleventh century; and his 

 paper gave an account of the work, with specimen 

 translations. The president of the society, Professor 

 Whitney of Yale, discussed a group of aorist-forms 

 in Sanscrit. The forms in question are of especial 

 interest, inasmuch as they furnish a good test-case 

 for the general trustworthiness of the Hindu science 

 of grammar, as compared with the most modern treat- 

 ment of the subject. Professor Bloomfield of Johns 

 Hopkins discussed the position of the Yaitana sutra 

 in the literature of the Atharva-veda, an important 

 text of which, the Kaucika sutra, he is now editing. 

 Several Syriac and Hebrew papers of value were pre- 

 sented ; but we must pass them by for want of suf- 

 ficient space. 



In Assyriology, finally, there was an account by 

 Professor Lyon of Harvard, of the last instalment of 



