744 



REPOUT — 1884. 



IS' 



eephalus Matthetvi the surface, in the first three stages of growth, appears smooth ; 

 in the fourth, tubercles begin to appear, and about the fifth stage all jjrojk'eting 

 parts of the test are studded with them. Those on the glabella and froutal iob« 

 are arranged in transverse rows ; those on the cheeks in interrupted rows conform- 

 ing more or less to the periphery of these protuberances. Towards the adult stape 

 these tubercles and spines become more irregular ir position and number, conform- 

 ing in this respect to the law of development in tlie .Ammonitts, expounded Ly 

 Profe^isor Alp'aonso Hyatt. 



3. Beport on the Bate of Erosion of the Sea Goasis of England aid 



Wales. — See Reports, p. 238. 



4. Fourth Report on the Earthqualce Phenomena of Japan, 



See Reports, p. 241. 



5. The Geology of Palesilns. By Professor E. Hull, LL.Z)., F.Ti.S. 



See p. 272. 



6. Notes on Niagara. By P. Hallf.tt, M.A. 



These notes may be expressed in abstract in the following propositions, and are 

 submitted to the Section as questions for its consideration. 



1. That, assuming the principle of the gradual formation of the cataract, the 

 condition of existence of the present overhanging precipice is the supenmpositin;i 

 of the hard Niagara limestone — corresponding to the Wenlock limestone — upon 

 the friable Niagara shale, the latter being undermined, and the former left fivtr- 

 hanging ; that the condition of existence of the rapids above the precipice is ib.e 

 succession of hard rocks simply, and that these diti'erences of condition probably 

 ditl'erentiate overhanging Falls from lipids generally. 



1'. Hence, in case of the precipice receding to a position above the shale, the Fall 

 would disappear and become a liapid. 



3. 'J hat the course of the water in the Rapids as an effect of increasing 

 velocity is convergent to mid-channel ; and hence the Rapids, instead of being a 

 source of danger to Goat Island and the small islands in their current, are actually 

 a protection to them by detei mining the water from their banks. 



4. That the water of the Fall undergoes a continuous disintegration from 

 summit to base, breaking up into smaller and smaller masses and spreadin;: 

 out as it descends. The ' continuous roar ' of Niagara is really a succession ol' 

 impulses. 



o. That this disintegration is a consequence of the collision between the falling; 

 ■water and the column of air beneath it ; and that the compressed air in its 

 descent is propelled inwards and outwards : inwards forming the well known rush 

 of winds behind the Falls, and driving the heading of excavation in the shale ; 

 outwards sending up the cloud mist that continuously hangs over the Falls. 



C. That this collision between the air and falling water is really a conservative 

 influence, distributing the direct force of the fall and partly transmitting it both 

 directly and by reaction along the currents of the gorge. 



7. That besides the force of the air propelled against the shale face of the 

 precipice as a cause of its excavation, attention is also to be directed to the 

 continuous drainage from the shale, as evidenced by springs, &c. Even aL>n<r 

 the gorge where there are no falls this appears to determine an undermining action 

 or recession of the banks below, with overhanging rocks above. 



8. That retrocession of the Falls, evident as it is, is not to be regarded as the 

 operation of a mechanical force necessarily continuous, but as a movement to 

 equilibrium. Hardly any retrocession has occurred in parts of the American Fall 

 during the time that the Canadian one has gone back some 500 yards. Retrocession 



. il u 



