MKMOllJS OF TJIK NATIONAL ACADHMY OF SCIENCES.' 169 



briskly over the inoistoiiod smiarc witli tlie tlmiiil) nail. Treat the entire Hpurc in this way. If 

 a nnersc iiii-ture is waiitt'il, wliich is usually (ho rase when a /iuishcd drawing is to be prepared 

 for eupraviiig, ink the scratched liiiii and take the imprint tlierefroui. 



If it is desired to prove tlm correctness of a po.sitive picture, wash away the ink from which 

 the imprint has been made, ink the scratched drawing and place it right sid(^ u])over the positive 

 on the i>ai<er. The two should correspond. In no instance where we have made this test have we 

 found the slijjhtest error. 



Wc liave used an ordinary black ink, and have been able to take three {^ood imi)re8sions from 

 one drawinj;. If it were desirable to take a large number of copies, other inks could be found to 

 a<complish tlie purpose. 



Dr. Paul Topinard tell us* that with Broca's stereograph the five views of the skull may be 

 made in an hour. It takes nearly twice that time tt) do the same with our contrivance, operating 

 with proper care; but as a partial compensation for this we have a drawing wliich furnishes many 

 duplicates. 



No special skill or lightness of hand is required with our apparatus; any person possessed of 

 ordinary intelligence and eyesight can use it successfully at the first trial. It is not complicated; 

 it requires no highly skilled workman to construct it; it nuiy be made by any carpenter and its 

 cost is insiginficaut. 



Even the periglyph may be made by any handy individual with an ordinary pocket knife. 

 We have two perigly])hs, one manufactured of metal by a practical model-maker, the other rudely 

 whittled out of wood by a medical gentleman connected with the Museum; both are perfectly 

 accurate, but the latter is the more easily handled and the favorite instrument. 



Several outlines may, without confusion, be drawn on the same varnished surface. The 

 varinsh should be of such a character that when dry it becomes crisp and brittle, breaking up in 

 the course of the stylus— not dragging after the instrument and clogging it. Of many mixtures 

 tried that known in the trade as Berry Brothers' (Detroit) hard-oil finish, diluted with one-third 

 turpentine, gave the best results. 



In making all but six of these tracings we adjusted the skulls on the German horizontal plane, 

 or plane of the Frankfort agreement, partly for the reason that with the sand box we could find 

 this i>lane more readily than we could find the alveolo-condylean plane. But for purposes of com- 

 parison we sketched the norma vertical in parallel with the alveolo-condylean plane in six speci- 

 mens, the type skull and five which approximated the tyije. The reduced tracings are shown in 

 plate 51. 



The five \-iews of the type skuUf (Pis. o.)-59, incl.) were nuule <m the basis of elaborate 

 orthogonal tracings, the sluuling being added by the artist from nature. They are natural size. 

 It is greatly to be regretted that the nasal bones in the type skull were broken, and that we were 

 obliged to make a plaster restoration. The shape of the nasal aperture is only approximate. 



There were but few .skulls in this .series in which all the points of the Gernmn horizontal plane 

 or any other horizontal plane could be found to coincide with a true horizon, while the sagittal 

 jdane was i>crfcctly vertical to such horizon. The variance was most marked at the upper borders 

 of the auditory meatuses. In order to approximate uniformity we always aligned our facial 

 guiding marks, not with the upper margin of the right meatus, but with that of the left, the side 

 on wliich the norma lateralis was taken. 



The views of the lower jaws in plates 52, 53, and 54 were taken with the same apparatus 

 and by the sanu', method as were those of the skulls, and similarly reduced by the pantograph. 

 When each was drawn the plate of glass on which the tracing was made was i)arallel to the i)lane 

 on which the lower margin of the jaw rested at equilibrium. 



Areas in thi- drawings marked with parallel straight lines show where there are holes in the 

 skulls, neither bone nor jdaster being present. Dotted areas indicate plaster restorations — all 

 such repairs, whether deep or superficial, being thus shown. 



'Op. cil., p. 863. t For deucriptiuu eve ^ 14. 



