Royal Society, 155 



truly instantaneous representation of an object in motion. The ex- 

 periment was conducted in the following manner. A printed paper 

 was fixed upon a circular disc, which was then made to revolve on 

 its axis as rapidly as possible. When it had attained its greatest 

 velocity, an electric battery, kindly placed at my disposal by Mr. 

 Faraday, was discharged in front of the disc, lighting it up with a 

 momentary flash. A camera containing a very sensitive plate of 

 glass had been placed in a suitable position, and on opening this 

 after the discharge, an image was found of a portion of the words 

 printed on the paper. They were perfectly well-defined and wholly 

 unaffected by the motion of the disc. 



As I am not aware that this experiment has ever succeeded, or 

 indeed been tried, previously, I have thought it incumbent on me to 

 lay an early account of it before the Royal Society. 



5. " The Human Iris ; its Structure and Physiology." By Bernard 

 E. Brodhurst, M.R.CS. Communicated by Thomas Bell, Esq., 

 Sec.R.S. &c. Received May 22, 1851. 



The author commences by stating that the iris is an active fibro- 

 cellular tissue, or that it may be considered to be a transition tissue 

 from the ordinary fibro-cellular to the organic muscular: that it is a 

 tissue differing from every other in the body; being possessed of 

 a motor power exceeding that of any other tissue, yet diff'ering in 

 construction and appearance of fibre from those other tissues, the 

 types of motion. 



He remarks that the microscope shows that the fibres of the iris 

 differ essentially from muscular fibre, whether striped or of organic 

 life : they are pale, easily separable and readily torn ; but they 

 resemble in no essential particular muscular fibre ; indeed, the 

 effect of galvanism on the iris is totally opposed to that produced 

 on muscular fibre. 



He observes that the nerves that pass to the iris are derived from 

 both motor, sensitive and negative nerves ; but voluntary motion is 

 not supplied, neither sensation. The motions of the iris are wholly 

 independent of the powers usually deemed motor ; they are influ- 

 enced primarily by the sympathetic system of nerves, through which 

 motion is accorded without sensation, motion without design. 



In death, the author observes, the iris assumes a median state, the 

 pupil being neither dilated nor contracted. In health, it is contracted. 

 Duringsleepit is contracted. During the presence of disease, thepupil 

 is dilated, and so much dilated beyond its usual state, as the tonicity of 

 the vegetative system is removed, as the presenceof disease operates on 

 the nutritive system to diminish not only the power of nutrition, but, 

 in a like degree, tension of the visceral system ; nutrition and tension 

 being as cause and effect of the healthy operation of this basic system 

 of the animal oeconomy. And as it is not essential to the motions of 

 the iris, either to their performance or that they be understood, that 

 they partake of many of those peculiarities, the distinguishing fea- 

 tures of iiiuscular tissue, and as we find that this membrane is 

 obedient to those laws which are applicable to each organ under 

 immediate sympathetic influence, and opposed to those phenomena 



