TRANSACTIONS OP THE SECTIONS. 211 



On the Navigation of the Clyde. By J. F. Ure. 



Concluding Address. Bij^V-i. Macquorn Rankine, C.E.,F.R.SS.L.8;E., 

 President of the Section. 



The papers read to this Section, though mimeroiis and interesting, have been of 

 moderate length, as is desirable. 



The discussions have been protracted, and have elicited many important facts and 

 suggestions. 



This is characteristic of discussions on questions of practical science. 



With respect to a question of physical theory, a philosophic inquirer suspends his 

 judgment until experimental data sufficient for its solution have been obtained — and 

 then there remains little room for dispute. 



On the contrary, a question of practical science usually involves the necessity for 

 the immediate adoption of some rule of worl^ing ; and if existing data are insufficient 

 to give an exact solution, that solution must be acted upon which the best data attain- 

 able show to be the most probable. A prompt and sound judgment on this point is 

 one of-the essential characteristics of a practical man — using that term in its best 

 sense. 



On such questions there is ample room, even amongst the best-informed, for differ- 

 ence of opinion and for discussion. 



Persons acquainted only with the sectional debates might, perhaps, conclude them 

 to be deficient in useful results ; but that conclusion would be most erroneous. 



We have had in this Section ample illustration of the benefit of such debates, in 

 eliciting the results of the experience of various engineers and mechanicians, and in 

 suggesting questions for further investigation. It is the duty of the Committee of the 

 Section to take such questions into consideration and to recommend to the General 

 Committee such measures as may appear necessary for their solution. Thus the 

 single week occupied by each Annual Meeting of the Association is a period of 

 receiving reports of work done by its members, and of planning fresh work for them; 

 while the period of working extends over the remainder of the year. 



The proceedings of this Section, during the meeting which is now about to close, 

 have involved an unparalleled amount of business, and have been fruitful in suggest- 

 ing important subjects for investigation. I think we are entitled to say, that much 

 has been done, during this meeting, to advance mechanical science, and to promote 

 the harmony between sound theory and good practice. 



The work to be done during the ensuing year, in consequence of the recommenda- 

 tions from the Committee of this Section, will be finally arranged to-day by the 

 General Committee; and I trust that we shall receive a good account of the per- 

 formance and effects of that work at our next meeting at Cheltenham. 



Appendix. 



On some Additions to the Geology of the Arctic Regions. 

 By J. W. Salter, F.G.S., A.L.S. 



[In an accompanying map were exhibited the discoveries lately made in Arctic 

 geology, and an attempt made to show at one view all that is now known on the 

 subject.] 



In a communication to the Geological Society, in 1853, I had the honour to de- 

 monstrate the existence of a wide-spread Upper Silurian formation in the lands 

 which border the Polar basin in North America. 



The fact, mentioned both by Conybeare and Jameson, of the chain coral being 

 found in the limestones of Barrow's Strait, would be, in the present state of our 

 knowledge, a sufficient proof of the existence of Silurian strata there. But it re- 

 quired the extensive collections made by the expedition under Capt. Austen along 

 that strait, and those made by Penny and his comrades up Wellington Channel, to 

 enable us to decipher the meaning of the old lists of fossils, and to show that an 



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