230 



NA TURE 



[January 7, 1892 



In the case of the clamper, marked c' in the drawing, 

 its action is to press the paper against the side of the 

 chamber during each exposure, and this is carried out by 

 means of a series of cams placed on a small circular hori- 

 zontal disk (marked c). It might be supposed that, with 

 very short exposures obtained by means of a very rapid 

 shutter, the clamper would be found quite unnecessary, as 

 the horizontal distance traversed by the band of paper 

 during an exposure would be practically nil, or at any 

 rate small enough to produce no visible effect on the 



lodoce, . . . passing on to scorpions and spiders, and 

 then to shrimps, lobsters, . . ." 



Although, at the first glance, one cannot quite see how 

 Muybridge's principle, or, at any rate, a slight change of 

 it, could be applied to interpret the gait of the centipede, 

 yet in Prof. Marey's instrument Prof. Lankester will, we 

 hope, find just the kind of apparatus to carry out the 

 various suggestions to which he referred. In fact, the 

 instrument has already been employed in producing 

 pictures representing aquatic locomotion, and the follow- 



FiG. 5. — The chamber in which the images are formed, with the Hd raised, m and R are the drums on which the films are rolled off and on respec- 

 tively; r, r, r, small rollers pressing the film on the cylinders; i., the driver, with ils pressing cylinder; F, the aperture for the admission of 

 the image ; v, ground glass with hinged motion. The dotted Imeindicjtes the path of the band of film ; c' and c, the clamper and its cam, which 

 produces the intermittent action of this band. 



picture produced ; but this is not the case, for Prof. 

 Marey says that by experience the only good images 

 obtainable were made with the use of the stop. 



Owing to the quickness of the action of the driver, 

 and the instantaneous blow given by the clamper to the 

 paper at each exposure, an elastic arm is rnade to come 

 into play to relieve the paper of any strain or force to 

 which it may be subjected. 

 ^Many readers may remember the very interesting 



ing illustration (Fig. 6) shows a Medusa swimming, while 

 Fig. 7 shows the phases of movement that a star-fish 

 undergoes in order to turn itself over. 



The interesting point is displayed in the last four pic- 

 tures of the series. Counting fn)m the bottom, No. 5 

 shows the position just before one of his " rays" leaves 

 the ground and just when he begins to grip it with the 

 other two ; having this grip, he is able to dispense with 

 the use of ihe other ray, and so raises the other three as 



Fig. 6. — Medusa swimming horizontally, whilst moving away rom the apparatus (negative). 



article in a former number of Nature (vol. xl. p. 78), 

 written by Prof. Ray Lankester, relating to the Muybridge 

 photographs. Towards the end he says : " For my own 

 part I should greatly like to apply Mr. Muybridge's 

 cameras, or a similar set of batteries, to the investigation 

 of a phenomenon more puzzling even than that of ' the 

 galloping horse.' I allude to the problem of ' the running 

 centipede.'" He then goes on to say : " I am anxious to 

 compare with these movements the rapid rhythmical 

 actions of the parapodia of such Chsetopods as Phyl- 



NO. 1 1 58, VOL. 45] 



; shown in No. 6, No. 7 illustrates the position of unstable 

 I equilibrium as obtained by means of the preceding move- 

 ments, while the last one exemplifies stable equilibrium 

 again. 



The time occupied in the above evolutions is not so 



short as may be supposed, but lasts sometimes from ten 



: to twenty minutes, the intervals in time between two of 



the above pictures being about two minutes. 

 I The movements of the eel have also been studied in 

 i this way, and the series of movements represented in 



