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��inilifi]' wicb tbese units is afHruied; but iu these two pages a clear understanding of tliem is made welt-nigh impossible. A single illus- tration will serve to show the character of many of those dc6nition8.

" The unit of tension is that tension (poten- tial differeuce) between two points which re- quires the expenditure of one unit of force (1 dyne) to move 1 coulomb from one point to the other by overcoming the electrical repul- sion (Dim. CilG-iS").

•■'■Technical unit, I volt = 10' (c. c. s.)

��BARNARD'S PYRAMID OF GIZEH.

Dr. Barnaud tells iis that Mr. Flinders Petrie, after having published a bool{ in \><ii to give' irrefragable proof ' of the supernatural metrology of the Great pyramid, in 1880 printed another in which he recants ail that doclvine. This surprising instance teaches us that it is possible fur a man to hold the views of John Taylor and Piazzi Smyth, and yet be capable of using his mind sanely ujion the subject. But Mr. Petrie had shown himself by his ' Inductive metrology ' to be an adept in the logic of induction; and surely one would expect the study of logic, if it be of any use at all, to save a man from such follies as this roetrological theory of the pyramid.

The muiu fuUacy of the advocates of it is one which has been pointed out in C. S. Peirce'a ' Theory of probable inference ' as a violation of the inductive rule that the characters for which a lot is sampled ought to be predesig- nntc; that is, settled upon before the exami- nation of the sample. Given a collection of numerical data, it is always possible, by twist- ing them about, to find some recondite and curious relationship between them; for the possibilities of such relationships arc endless. 5Ir. Pliny Earle Chase has convinced the world of that, 'if of nothing else.

Another thing which the pyramid -bitten seem to overlook, is that an hypothesis ante- cedently likely does not mean one which they are antecedently inclined to like, but one which belongs to a class of explanations among which the balance of positive evidence tends to show that the true theory is to be looked for.

Dr. Barnard treats the subject with a great deal of portineut wit; he has drawn from the stoi-es of his learning for interesting informa-

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�� ��tion on every page; and, what is beat, I estimated the strength of each argument Witt 1 unerring good sense. Perhaps he is a little too indulgent to the idea that the vertical height of the pyramid was intended to bear the same ratio to the perimeter of the base that the radius of a circle bears to its diameter. Fourteen centuries after the building of the Great pyra- mid under King Apophis of the seventeenth dynast)' (Joseph's Pharaoh, as it is said), was written the mathematical treatise of AhmcB. which has been preserved to us. This work virtually assumes

T - W = 3.18, and there is no good reason for supposing that the pyramid-builder knew belter. On the contrary. Sir Henry James's idea is probably correct, that the rule for the slope was, that at the corners the rise should be nine on a base of ten.

The supposition that the inclination of the en trance- passage was eonnectetl with a pole- star, derives, it would appear, ite chief strength from its forming a part of Mr. Procter's ingen- ious theory of the orientation of the pyramid, which certainly iias much to recommend it; yet the accuracy of orientation may be merely accidental, like that of the District of Colum- bia. ,

��NOTES AND NEWS. tin. H. U. Wahnisr of Rochealsr, N.Y., offers two prizes for the jear 18U5. First, two hundred dollKn for uacli und every discovery of a new comet made i from Feb. 1, 1SS5. to Feb. 1, 1886, subject to the fol- , lowing conditions: 1. It must be discovered Id the i ITuited States, Canada, Mexico, West ludiea, Soutb America, Great Britain, or the Australian continent j and Islands, cither bj the naked eye or teleicope. and it must be unexpected, excepts to the comet of ISI&, which is expected to re-appear ttiis year or next; 2. ' The discoverer must send a prepaid telegram imme- diately to Dr. Lewis Swift, director, Warner observa- tory, Rochester, N.Y., giving the time of the discovery, the position and direction of motion, with sufflclent exactness, If possible, to enable at least one other observer to find It; 3. This iutelligcnce must not be eommunicatcd to ang other partp or parties, either by letter, telegrapb, or otherwise, uulil such time as a telegraphic acknowtedgroeut has been received by the discoverer from Dr. Swift {great care should be observed regarding this condition, as It Is essential to the proper transm^sion of the discovery, with the name at ilie discoverer, to the various parts of the world, which will be immediately made by Dr. SwKt]. Discoverers In Qreat Britain, the Australian cont4- nent and Islands, West Indies, and South America, are absolved from the restriction in conditions 2 and 3. Second, a prize of Iwo hundred dollars lu gold to

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