Mr. Spiller's Analyses of a Babylonian Cylinder and Amulet. 107 



If it be assumed that the axis about which the rotation takes 

 place goes through the centre of the aperture^ the water particles 

 which are in the one half of this aperture will be moved by the 

 rotation in an opposite direction to those in the other half. In 

 consequence of this rotation^ the particles, after they have left 

 the aperture, do not fall verticallj'-, but deviate from the vertical ; 

 those in the one half deviate towards the one side, and those in 

 the other towards the opposite side. Hence the edges of the jet 

 are not in a plane, and encounter either not at all, or at any rate 

 not centrally. Hence the jet assumes, as remarked above, the 

 spiral shape, fig. 16 a and b. 



58. If the rotation in the vessel be very violent, the two edges 

 deviate, soon after the liquid has left the vessel, so strongly in 

 opposite directions, that the water mass between them separates, 

 and both edges continue their way as two separate jets, moving 

 often at a considerable angle to each other. 



59. The ease with which the rotation of the liquid in the 

 vessel occurs, or rather the difficulty of avoiding it without using 

 the tranquilizer, is the reason why the jet in its regular form, 

 fig. 15 fl and b, has hitherto been seldom observed. 



60. Phfenomena quite analogous to those which the jet from 

 an elongated rectangular oriuce presents, are seen if the water 

 be allowed to fliow in a similar thin layer over the edge of a 

 vessel; but the forms which are then presented are seldom 

 regular. 



The difierent forms of a jet issuing from an elongated quadri- 

 lateral aperture, which have been described in the preceding 

 sections, afford a point d'appui for the peculiar forms presented 

 by other apertures. 



[To be continued.] 



XII. Analysis of a Babylonian Cylinder and Amulet. By John 

 Spiller, Metallurgical Laboratory, Museum of Practical 

 Geology *. 



IN the British Museum there is a large collection of engraved 

 cylinders, seals, &c. of Assyrian workmanship, the results 

 of the researches of Layard, Rawlinson, and Loftus. They are 

 chiefly composed of natural mineral substances, such as rock- 

 crystal, agate, carnelian, serpentine, lapis-lazuli, &c. ; there is 

 also one of shell, and another of glass. There are two varieties, 

 however, of which the composition was doubtful, and the follow- 

 ing analyses were made for the purpose of determining their 

 chemical constitution. The specimens operated upon were 

 received directly from Mr. W. Kennett Loftus. 



"* Communicated by the Author. 

 12 



