Dec. 1st, 1887.] 



SCIENTIFIC NEWS. 



227 



THE POLYGRAPH. 



MANY of our readers are doubtless familiar with this 

 ingenious instrument, which consists of a disc (shown 

 in Fig. i) perforated and stamped in such a manner as to 

 combine in itself the qualities of straight and curved rules, 

 dividers, protractors, and scale. It is useful in elementary 

 schools for teaching correctness of eye, and for laying the 

 foundation of accuracy in geometrical drawing, as with a 

 little care and practice figures (such as those shown 

 in Fig. 2) can be drawn easily and quickly by young 

 children. 



DEFINITION OF SCIENCE. 



WE borrow the following definition from a contempo- 

 rary: — "Science is not mere knowledge. No accumu- 

 lation of facts, however important in themselves, and how- 

 ever accurately observed and faithfully recorded, constitutes 

 a science. The facts must be co-ordinated and shown forth 

 in their relations of co-existence and succession. If this has 

 not yet been done, or if from the arbitrary and casual 

 nature of the facts it cannot be done, the study is erudition, 

 or learning, but not science. 



"Science must also be carefully distinguished from the arts. 



Fig. 



The Method of Using the Polygi^aph. 



Fig. 



Specimen of Designs Made with a Polygraph. 



Luminous Organs of a Fire-Fly. — Dr. Dubois has inves- 

 tigated the light-emittingorgans of the ciicuyo, ox Pyrophorus 

 noctilucus. They are three in number — two prothoracic 

 and one ventral. The prothoracic plates give a good illu- 

 mination in front, laterally, and above, and serve when the 

 insect walks in the dark ; when it flies or swims, its fine 

 abdominal lantern is unmasked, throwing downward an 

 intense light with much greater range. The insect seems 

 to be guided by its own light. If the prothoracic apparatus 

 is quenched on one side with a little black wax, the cucu3'o 

 walks in a curve, turning toward the side of the light. If 

 both sides are quenched, it walks hesitatingly and 

 irregularly, feeling the ground with its antennae, and soon 

 stops. The light gives a rather long spectrum from the red 

 to the first blue rays ; it is more green than the light of 

 Lampvi'is noclilitca, and has aphotographicaction,but does not 

 develop chlorophyll. No distinct electric action could be 

 traced in the organs. The luminosity does not depend upon 

 oxygen, for it is the same in pure oxygen, in air, and at 

 pressures under one atmosphere. The organs are still 

 brilliant when separated from the body, but the power of 

 emission appears to depend upon a supply of water, and it 

 is recoverable, after thorough drying, upon putting the 

 organs again in water. Dr. Dubois found that the photo- 

 genic substance is an albuminoid, soluble in water and co- 

 agulable by heat ; it entering into contact with another sub- 

 stance of the diastaste group, part of the energy liberated 

 appears as light. 



whether fine, useful, or useless. Science sees phenomena, 

 records them, traces their laws, and to this end questions 

 nature, her sole object being truth. Where completely suc- 

 cessful she attains prevision. 



" Art, on the contrary, seeks to produce, to modify, or to 

 destroy. Her sphere is action. She aims at power and 

 enjoyment, and where completely successful she creates." 



Popular Education. — The London Society for the Exten- 

 sion of University Teaching has arranged to hold courses of 

 lectures at Essex Hall, Strand. Among the subjects for the 

 short courses of three weekly lectures is "Electricity in the Ser- 

 vice of Man," by Mr. W. Lant Carpenter, B.A., B.Sc, M.S.T.E. 

 The admission fee to each lecture is one penny. 



Prizes for Art Workmen. — The articles in competition for 

 the prizes offered by the Society of Arts must be delivered on or 

 before Saturday, December 3rd. 



COCAINE. 



THE benefit of cocaine in the removal of pain from 

 mankind has been found to be second only to chloro- 

 form. From the coca leaf has been produced an anaesthetic 

 which can deaden any part of the human frame, so that a 

 successful operation can be performed at that place without 

 affecting the brain or weakening any other part. Coca, 

 the dried leaf of the Erathroxylon coca, belongs to a class of 

 stimulating narcotics, but it is more remarkable than either 

 tobacco or opium in its effect upon the human frame. It is 



