through such long distances. It consists essentially of a jib made
of single I-sections, and supported by tie-rods (fig. 21), the load to be
lifted being suspended from a small travelling carriage which runs
on the lower flange.
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| Fig. 21. |
The lifting gear is located in any convenient fixed position. In order that only one motor may be used, and also that the load may be lifted by a single part of rope, various devices have been invented. The jib is usually inclined, so as to enable the travel to be performed by gravity in one direction, and the object of the transporter mechanism is to ensure that pulling in or slacking out the lifting rope shall perform the cycle of operations in the following order:—Supposing the load is ready to be lifted out of a vessel on to a quay, the pull of the lifting rope raises the load, the travelling jenny being meanwhile locked in position. On arriving at a certain height the lift ceases and the jenny is released, and by the continued pull of the rope, it runs up the jib; on arriving at an adjustable stop, the jenny is again locked, and the load can be lowered out; the hook can then be raised, when the jenny is automatically unlocked, and on paying out the rope the jenny gravitates to its first position, when the load is lowered and the cycle repeated. The jibs of transporters are often made to slide forward, or lift up, so as to be out of the way when not in use. Transporters are largely used for dealing with general cargo between vessels and warehouses, and also for coaling vessels; they have a great advantage in not interfering with the rigging of vessels.
Nearly all recent advances in crane design are the result of the introduction of the electric motor. It is now possible to apply motive power exactly where it is wanted, and to do so economically, so that the crane designer has a perfectly free hand in adding the various motions required by the special circumstances of each case.
The literature which deals specially with cranes is not a large one, but there are some good German text-books on the subject, amongst which may be mentioned Die Hebezeuge by Ernst (4th ed., Berlin, 1903), and Cranes, by Anton Böttcher, translated with additions by A. Tolhausen (London, 1908). (W. P.*)
CRANIOMETRY. The application of precise methods of measurement marks a definite phase in the development of most branches of modern science, and thus craniometry, a comprehensive expression for all methods of measuring the skull (cranium), provides a striking landmark in the progress of anthropological studies. The origin of craniometry appears to be twofold. Certain artists made measurements of heads and skulls with a view to attaining greater accuracy in their representation of those parts of the human frame. Bernard de Palissy and A. Dürer may be mentioned as pioneers in such researches. Again, it is clearly shown in the literature of this subject, that anatomists were led to employ methods of measurement in their study of the human skull. The determining cause of this improvement in method is curious, for it appeared at the end of a famous anatomical controversy of the later middle ages, namely the dispute as to whether the Galenic anatomy was based on the study of the human body or upon those of apes. In the description of the dissection of a chimpanzee (in 1680) Tyson explains that the measurements he made of the skull of that animal were devised with a view to exhibiting the difference between this and the human skull.
The artists did not carry their researches very far. The anatomists on the contrary continued to make measurements, and in 1764 Daubenton published a noteworthy contribution to craniometry. Six years later, Pieter Camper, distinguished both as an artist and as an anatomist, published some lectures containing an account of his craniometrical methods, and these may be fairly claimed as having laid the foundation of all subsequent work. That work has been described above as anthropological, but as the studies thus defined are very varied in extent, it is necessary to consider the subdivisions into which they naturally fall.
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| Fig. 1.—The Skull and head of a young orang-utan, and of a negro, showing the lines including the facial angle (MGND) devised by Pieter Camper. |
In the first place (and omitting further reference to the contributions of artists), it has been explained that the measurements were first made with a view to elucidating the comparison of the skulls of men with those of other animals. This wide comparison constitutes the first subdivision of craniometric studies. And craniometric methods have rendered the results of comparison much more clear and comprehensible than was formerly the case. It is further remarkable that among the first measurements employed angular determinations occur, and indeed the name of Camper is chiefly perpetuated in anthropological literature by the “facial angle” invented by that artist-anatomist (fig. 1). It appears impossible to improve on the simple terms in which Camper describes the general results of the employment of this angle for comparative purposes, as will appear from the following brief extract from the translation of the original work: “The two extremities of the facial line are from 70 to 80 degrees from the negro to the Grecian antique: make it under 70, and you describe an ourang or an ape: lessen it still more, and you have the head of a dog. Increase the minimum, and you form a fowl, a snipe for example, the facial line of which is nearly parallel with the horizon.” (Camper’s Works, p. 42, translated by Cogan, 1821.)
In the 19th century the names of notable contributors to the literature of craniometry quickly increase in number; while it is impossible to analyse each contribution, or even record a complete list of the names of the authors, it must be added that for the purposes of far-reaching comparisons of the lower animals with mankind, craniometric methods were used by P. P. Broca in France and by T. H. Huxley (figs. 2 and 3) in England, with such genius and success as have not yet been surpassed.
The second division of craniometric studies includes those in which the skulls of the higher and lower races of mankind are compared. And in this domain, the advent of accurate numerical methods of recording observations brought about great advances. In describing the facial angle, it will be seen that the modern European, the Greek of classical antiquity and the Negro are compared. Thus it is that Camper’s name appears as that of a pioneer in this second main division of the subject. Broca and Huxley cultivated similar comparative racial fields of research, but to these names that of Anders Retzius of Stockholm must be added here. The chief claim of Retzius to distinction rests on the merits of his system of comparing various dimensions of the skull, and of a classification based on such comparisons. These indices will be further defined below. It is convenient to mention here that the first aim of all these investigators was to obtain from the skull reliable data having reference to the conformation or size of the brain once contained within it. Only in later days did the tendency to overlook this, the fundamental aim and end
