September i, 1904] 



NA TURE 



437 



rich philanthropists might be found, but in most cases it 

 would be impossible to form a company on business lines, 

 under the existing laws of this and other countries, as I 

 shall endeavour lo show. 



In the case of many of the problems, no patents will give 

 adequate protection : in some cases there is no subject-matter 

 of novelty and importance involved. In other cases the 

 probable duration of the investigation is so long that any 

 initial patents would have e.\pired before a commercial result 

 was reached, and in either of these circumstances there 

 would be no inducement to business men or financiers to 

 undertake the risk. 



.As an illustration of my meaning I will take two investi- 

 gations that have doubtless occurred to the minds of most 

 of those present, though many others of greater or less 

 importance might be cited. One is the thorough investi- 

 gation of the problem of aerial navigation, with or without 

 the assistance of flotation by gas. This problem could 

 undoubtedly be successfully solved by an organised attack 

 of skilled and properly trained engineers and the expenditure 

 of a large sum of money. -Assuming the problem solved, 

 and commercially successful, it appears to be impossible 

 under the e.xisting patent laws to secure any adequate 

 monopoly so as to justify the expectation of a reasonable 

 return on the capital expended on the invention. For in 

 view of the multitude of suggestions that have been made 

 and the experiments that have been carried out, the practical 

 solution of the problem would appear to rest on a judicious 

 selection of old ideas by means of exhaustive experiments. 



Another and perhaps more important investigation which 

 has not, as yet, been attacked to any material extent is the 

 exploration of the lower depths of the earth. .At present 

 the deepest shaft is, I believe, at the Cape, of a little more 

 than one mile in depth, and the deepest bore-hole is one 

 made in Silesia, by the Austrian Government, of about the 

 same depth. What would be found at greater depths is at 

 present a matter for conjecture, founded on the dip and 

 thicknesses of strata observed on or near the surface. Much 

 money and many valuable lives have been devoted to ex- 

 ploration of the polar regions, but there can be no com- 

 parison between the scientific interest and the possible 

 material results of such exploration and the one I have 

 chosen for illustration of the inadequate protection afforded 

 by law — namely, a great engineering attack on a problem 

 of geology. 



I would ask you to consider the commercial aspect of 

 this engineering geological enterprise, as compared with 

 exploration into new or unknown areas on the surface of 

 the earth. 



.An exploring expedition into a new country has before it 

 generally the probability of the acquisition of territorial 

 and mineral rights or possessions bringing material gain 

 to the undertakers. The rights of such enterprises are well 

 known, and capital can be obtained with or without national 

 support, as the case may be. On the other hand, the 

 explorer into the depths of the earth has no rights or 

 monopolies beyond the mineral rights of the land he has 

 purchased over his boring; further, it is improbable that he 

 can obtain any patent of substantial value for his methods 

 of boring to great depths. To succeed in the undertaking 

 a great expenditure of money must be incurred, an expendi- 

 ture far greater than that of an exploring expedition, and 

 analogous to that of a military expedition or a small in- 

 vading army, and to raise this sum the pioneers have 

 practically no security to offer. For if they succeed in find- 

 ing rich deposits of precious minerals in greater abundance, 

 or succeed in making some geological discovery associated 

 with deep borings, they gain no exclusive title to these 

 under existing laws. Any other person or syndicate acting 

 upon the experience gained, could sink other shafts in other 

 places or countries, and, benefiting by the experience gained 

 by the pioneers, could probably carry out the work more 

 advantageously, and thus depreciate the first undertaking or 

 render it valueless, as has often occurred before. 



Let us consider more closely some of the essential features 

 of sinking a shaft to a great depth, for I think it will be 

 seen that it presents no unsurmountable difficulties beyond 

 those incidental to an enterprise of considerable magnitude 

 involving the ordinary methods of procedure and the 

 ordinary methods adopted by 'mining engineers. That 

 there would be some departures from ordinary practice on 



NO. 18 1 8, VOL. 70] 



account of the great depth is true, but these are more of 

 the character of detail. On the design of this boring I have 

 consulted Mr. John Bell Simpson, the eminent authority on 

 mining in the North of England. The shaft would be sunk 

 in a locality to avoid as far as possible water-bearing strata 

 and the necessity of pumping. It would be of a size usual 

 in ordinary mines or coal-pits. The exact position of such 

 shaft would require some consideration as to whether it 

 should commence in the primary or secondary strata. It 

 would be sunk in stages, each of about half a mile in depth, 

 and at each stage there would be placed the hauling and 

 other machiner}', to be worked electrically, for dealing with 

 each stage. The depth of each stage would be restricted to 

 half a mile in order to avoid a disproportionate cost in the 

 hauling machinery and the weight of rope, as well as in- 

 creased cost in the cooling arrangements arising from 

 excessive hydraulic pressures. At each second or third mile 

 in depth there would be air-locks to prevent the air-pressure 

 from becoming excessive owing to the weight of the super- 

 incumbent air, which at from two to three miles would reach 

 about double the atmospheric pressure at the surface. A 

 greater rise of pressure than this would be objectionable for 

 two reasons — firstly, from the inconvenience to the work- 

 men ; secondly, from the rise of temperature due to the 

 adiabatic compression of the circulating air for ventilating 

 purposes. The air-pressure immediately above each air- 

 lock would thus reach to about two atmospheres, and 

 beneath to one atmosphere. In order to carry on the transfer 

 of air through the air-locks for ventilating purposes pumps 

 coupled to air-engines would be provided, the energy to 

 work the pumps being obtained from electro-motors. To 

 maintain the shaft at a reasonable temperature at the greater 

 depth powerful means of carrying the heat to the surface 

 would be' provided. 



The most suitable arrangement for cooling would prob- 

 ably consist of large steel pipes, an upcast and a downcast 

 pipe, connected at the top and bottom of each half-mile 

 section in a closed ring. This ring would be filled with 

 brine, which by natural circulation would form a powerful 

 carrier of heat ; but the circulation, assisted by electrically 

 driven centrifugal pumps, would be capable of carrying 

 an enormous quantity of heat upwards to the surface. At 

 each half-mile stage there would be a transfer of the heat 

 from the ring below to the ring above by means of an 

 apparatus similar in construction to a feed-water heater, 

 or to a regenerator constructed of small steel tubes, through 

 which the brine in the ring above would circulate, and 

 around the outside the brine in the ring below could also 

 circulate, the heat being transmitted through the metal of 

 the tubes from brine ring to brine ring. 



We have now presented to us two alternative arrange- 

 ments for cooling. One arrangement would be to cool the 

 brine to a very low temperature in the top ring at the mouth 

 of the shaft by refrigerating machinery, so as to provide a 

 sufficient gradation of temperature in the whole brine 

 system, to ensure the necessary flow of heat upwards from 

 brine ring to brine ring, and overcome all the resistances 

 of heat-transfer, and so maintain the lowest ring at the 

 temperature necessary for effectual cooling of the lowest 

 section of the shaft. But a better arrangement would be 

 to place powerful refrigerating machinery at certain of the 

 lower stages, the function of this machinery being to extract 

 heat from the ring below and deliver it to the ring above. 

 This latter method would increase to a very great extent 

 the heat-carrying power of the system, which in the first 

 arrangement is limited by the freezing temperature of brine 

 in the descending column and the highest temperature 

 admissible in the ascending brine column. The amount 

 of heat conducted inwards through the rock-wall and 

 requiring to be absorbed and transferred to the surface 

 depends on the temperature and conductibility of the strata. 

 But there is no doubt that the methods I have indicated 

 would be capable of maintaining a moderate temperature in 

 the shaft to depths of twelve miles. 



During the process of sinking at the greater depths the 

 shaft bottom would require the application of a special 

 cooling process in advance of the sinkers, similar to the 

 Belgian freezing system of M. Poesche used for sinking 

 through water-bearing strata and quicTcsands, and now in 

 general use. It consists in driving a number of bore-holes 

 in a circle outside the perimeter of the shaft to be sunk ; 



