Progress of Invention. 473 



form, and one of a very remarkable character, of Saurian ware, 

 apparently of the very late Roman period. The collection of early 

 Frankish and Germanic antiquities is also most interesting, and is 

 well worthy of study — especially some of the Frankish weapons, in 

 iron, such as swords, battle-axes, spear-heads, and bosses of shields. 

 The remains of the Christian Frankish age are also rather nume- 

 rous, including some fine examples of coffers and reliquaries, and some 

 exceedingly interesting specimens of early enamel. The continuous 

 museum of mediaeval art and workmanship in the Exhibition build- 

 ing is very complete, and is arranged with judgment in its different 

 historic periods. Each is rich in its peculiar illuminated manu- 

 scripts, in its sculptured ivories, and in an infinite variety of objects, 

 which it would be quite impossible even to enumerate here, and it 

 would be difficult, without much, more space at our disposal, to 

 make even a selection. The show of early enamels of Limoges is 

 something wonderful. T. W. 



PROGRESS OF INVENTION. 



New Photographic Instrument. — An ingenious apparatus, termed 

 by the inventor a Photographometer, and intended to record the 

 angular position of objects situated around a given point, has been 

 constructed by M. Chevallier. It is entirely automative, and very 

 simple, so that it maybe used by those possessing but little manipu- 

 lative skill. The record is made by photography, and the camera 

 used, with the exception of certain additions, does not differ much 

 from the ordinary kind. The objective, which is that usually 

 employed by photographers, is mounted vertically on a circular 

 platform capable of rotating, by means of clockwork, in a horizontal 

 plane. The picture is formed, not in a vertical plane, as in ordinary 

 cases, but in a horizontal ; and therefore the rays passing in through 

 the objective are deflected 90° by means of a reflecting prism, so as 

 to fall on the sensitive surface, which is collodionized glass, and 

 is placed in such a way that its centre corresponds with the point 

 at which the centre point of the diaphragm would be represented. 

 To prevent a number of confused images, superimposed on each 

 other, being formed during the rotation of the objective, an opaque 

 screen, having a narrow oblong opening, the median line of which 

 passes through the axis of rotation, is placed over the whole of 

 the sensitized surface, and revolves along with the objective. The 

 result of this arrangement is the production on the- sensitized plate 

 of images of the different points that lie around the observer ; the 

 angles formed by lines joining the centre of the plate, and t\\Q 

 different objects being exactly the same as those formed by lines 

 joining the centre of the instrument, and the objects themselves. It 

 is evident that the position of the objects thus accurately obtained 

 may be transferred to paper, etc., in the ordinary way. As different 

 velocities of rotation may be suited to different purposes, three 

 different velocities may be obtained by means of a regulator. And 



