824 EVENING DISCOURSES. 



thirty-five beats of the wings — it has two pairs — per second. The electric spark 

 was used, and by this means an enormous number of exposures per second can be 

 obtained. The wings make a figure of 8 movement from behind forward, while 

 in birds the figure of 8 described by Pettigrew is from above downwards. 



The following table from Marey shows the number of vibrations per second 

 made by the wings of certain insects : — ■ 



Name. Per Second. 



Common Fly 330 



Drone Fly . . 240 



Bee . 190 



Wasp 110 



Humming-bird Moth 72 



Dragon-fly 28 



Butterfly, White 9 



The work of Borelli on the flight of birds was illustrated by a copy of Borelli's 

 original figure. The splendid work of Marey by the graphic and photographic 

 methods was referred to. There is one striking fact about the flight of birds — 

 viz., that the pectoral muscles which move the wings are equal to one-sixth of the 

 total weight of the animal. The following table from Marey shows the number 

 of vibrations per second : — 



Name. ' Per Second. 



Sparrow 13 



Wild Duck 9 



Pigeon 8 



Moor Buzzard 6 



Screech Owl ........... 5 



Buzzard ........... 3 



The last part of the lecture dealt with reflex action as the physiological unit 

 in the operations of the nervous system, the subject being represented by the 

 reflex movements of a pithed brainless frog, and by the protective reflexes of such 

 animals as crabs, lizards, &c. , which, as shown by Fredericq, amputate a limb or 

 the tail when limb or tail is violently seized. That animals can still execute well 

 co-ordinated movements after certain injuries to the nervous system was illustrated 

 by showing a film of a frog climbing an inclined plane and maintaining its 

 equilibrium after removal of its cerebrum. The stepping movements of a dog, in 

 which Professor Sherrington had completely divided the spinal cord, were also 

 shown. As to the movements of internal organs, some films were projected to 

 show the heart beating after removal from the body of the frog, tortoise, and 

 rabbit. The last films showed the excised heart of a rabbit, prepared by Dr. Locke 

 and perfused with his fluid, beating and recording its beats on a moving 

 blackened cylinder, the effects of chloroform on its beats, stopping them, and 

 the recovery of the beat after washing out the chloroform ; and to give an example 

 of a rhythmical beat due to alterations of surface tension, the rhythmical beats 

 of a globule of mercury, known as ' Ostwald's physical heart,' were projected. 



MONDAY, SEPTEMBER 5. 



Recent Hittite Discovery. By D. G. Hogarth, M.A. 



The object of the lecture was to show in outline how the memory of the Hit- 

 tites as an imperial people has been recovered and what their place in world- 

 history was. This recovery dates from the finding in 1834-35 of two prehistoric 

 cities at Boghaz Keui and Uynk in North- Western Cappadocia. Their sculptures 

 and inscriptions were ultimately recognised by Sayce as belonging to the same 

 family as certain inscriptions and sculptures which had been found at Hamath 

 and elsewhere in Syria after 1870, ard also some other monuments observed in 



