382 



NATURE 



{Feb. 27, 1879 



" Type B. All heat rejected from the cylinder unutilised 

 may be gathered up and restored to the boiler, there to 

 serve as a basis upon which to pile a new stock of trans- 

 formable heat-energy, instead of being, as now, rejected 

 from the system entirely and lost. This done, there 

 could be no loss, as all heat leaving the machine would 

 be transmitted to exterior bodies as mechanical energy. 

 Nothing being lost as heat, the efficiency of the engine 

 would be unity and its economy a maximum. 



" Forms of steam-engines may be conceived in which 

 these methods (of saving heat now wasted) may be applied. 

 Practically, however, it is evident, the first form of these 

 two ideal engines can never be made successfully, since 

 it would require to be made of such immense size that 

 all the power derivable from it would be insufficient to 

 move it." 



An instance of the Type B is given. It is proposed to 

 expand the steam in the cyUnder until it is half liquefied, 

 then separate the water from the steam and return them 

 separately to the boiler, whereupon it is concluded. 



" Under the conditions now assumed, it is evident that 

 only that portion of the heat entering the engine which is 

 surrendered by the condensation of steam doing work can 

 be utilised. It is also evident that, in this form of engine, 

 no heat can be lost ; and, consequently, that the engine 

 of Type B, which is operated as just indicated, will have 

 yielded the exact equivalent of the net amount of heat 

 expended upon it. All heat rejected from the working 

 cylinder, unutilised, being returned to the boiler, there to 

 form 'a basis on which to pile up a new stock of utilisable 

 energy,' the engine is a 'perfect engine' in a broader 

 sense than that adopted by Carnot. It is further evident 

 that perfect efficiency is given for all ranges of tempera- 

 ture, and that what working fluid shall be adopted, and 

 what temperatures shall be chosen, will be determined 

 simply by practical conditions to be ascertained by expe- 

 riment. . . . 



" When this possible ' engine of the future ' is likely to 

 be introduced, if at all, can be scarcely even conjectured. 

 It seems evident that its success is to be secured, if its 

 introduction is ever attempted, by the adoption of high 

 steam-pressures, of great piston-speeds, by care and skill 

 in design, by the use of exceptionally excellent materials 

 of construction, by great perfection of workmanship, and 

 by intelligence in its management. There seems no 

 tangible obstacle to its introduction." ^ 



KIN AH AN' S GEOLOGY OF IRELAND 

 Manual of the Geology of Ireland. By G. St. Kinahan, 

 M.R.I.A., &c. (London : C. Kegan Paul and Co., 1878.) 



THE appearance of another volume on Irish Geology, 

 so soon after that of Prof. Hull, seems to show that 

 the geologists of the Emerald Isle can be as active with 

 their pens as with their hammers. Mr. Kinahan, indeed, 

 has just claims to be heard when he treats of the rocks of 

 his native country, for we suppose there is hardly any 

 other living Irishman who has worked so long and so 

 continuously among them. His volume, of course, 

 coming before us as it does, cannot but challenge com- 

 parison with that of his director, Mr. Hull ; and in truth 

 it would almost appear as if this had been, consciously or 

 not, in his mind. The two books, however, are on two 

 very different plans. The general reader who wishes a 



I "The idea first suggested itself to the mind of the writer in 1858-59, when 

 at Brown University, and while designing a peculiar form of ' drop cut-off 

 engine,' which was intended to work with exceptional economy. The plans 

 then conceived have gradually assumed a different shape, but still embody 

 the essential principles here outlined. Mr. C. E. Emery, in 1868, proposed 

 a similar plan. " 



pleasantly-written sketch of Irish geology, and of its 

 relation to the scenery of the island, will find what he 

 needs in Prof. Hull's chapters. Mr. Kinahan's work is 

 more suited for professed geologists who propose to visit 

 Ireland, and want to hare some idea of the best districts 

 to visit for their special purpose. 



The volume is divided into five sections. In the first 

 the author describes the sedimentary formations of 

 Ireland, going over the country district by district, and 

 pointing out in a useful, if somewhat prolix manner, the 

 peculiarities of each. In the second he enters upon more 

 speculative matter in an account of metamorphic and 

 eruptive action as displayed among the Irish rocks. The 

 third is devoted to the superficial accumulations, in- 

 cluding the drift, the proofs of glaciation, changes of 

 level, peat-bogs and prehistoric remains, and extinct 

 mammalia. In the fourth section a brief description of 

 the physical features is given from the writer's own point 

 of view. The remaining division treats of the economi- 

 cally useful minerals of the country. 



One cannot read Mr. Kinahan's pages without recog- 

 nising his sturdy force of character. He takes up a 

 position and holds it, one might almost think sometimes 

 against his better judgment. It is satisfactory, however, 

 to find him willing to yield sometimes, as, for instance, in 

 his relinquishment of the absurd j//^ termination of rocks, 

 though he takes care to inform us that while he yields to 

 the entreaties of publishers and friends, he remains of the 

 same opinion still. What a labour it must have been 

 originally to change all his i-s into y-s ! There are some 

 other matters of orthography or even of grammar, which, 

 when he feels himself to be in a compliant temper, he 

 may take into his consideration. Why does he so 

 constantly speak of "Cambrians" and "Silurians?" 

 These are adjectives, and not nouns, and though in the 

 field-slang of the Geological Survey, or of geologists 

 generally they may be tolerated, they ought not to appear 

 in any grave published work. 



In the first section of the book it will probably occur to 

 most readers that there is a want of breadth in the treat- 

 ment of the subject. The local details are valuable as 

 guides to the places and for the scattered facts they 

 contain. But they lack that connecting thread which 

 would have strung them all together and have carried the 

 reader intelligently along, instead of leaving him, as he 

 can hardly help feeling, struggling after the seven- 

 leagued strides of Mr. Kinahan as he hops from district 

 to district. Brief summaries for the separate regions, and 

 a general connected summary of the whole for the system 

 or formation, would have given the reader the key to the 

 details. And as regards these details we fear they are 

 often too vague to be of as much service to the field- 

 geologist as he would wish them to be. The kind of 

 detail he needs is supplied by the valuable " Explanations 

 of the Geological Survey of Ireland." Mr. Kinahan often, 

 indeed, refers to these "Explanations," but he would have 

 given his volume a more practically useful character had 

 he inserted in the account of each district a reference to 

 the particular explanation in which a fuller description 

 may be found. Such references, for the purposes of the 

 student and the geologist who wants to study the matter 

 on the ground, cannot be too precise and frequent. As 

 it is, Mr. Kinahan's chapters on the rocks and struc- 



