THE EFFECT OF PROPELLERS ON THE STEERING OF VESSELS. 



419 



These analyses show, in the words of the. Commission, " that the oolitic 

 rocks are not inferior to the New Red Sandstone, in the energy with 

 which they oxidize and destroy the organic matter present in the waters 

 percolating through them." 



Though the waters so derived are generally hard, it is chiefly of a 

 temporary character, capable of being softened by Clark's process, so as 

 to average 6° - 8 instead of 20 o- 6. 



The oolites yield in springs and deep wells, water which is " bright, 

 sparkling, and palatable," and " excellent for drinking and all domestic 

 purposes, except washing," for which latter purpose, the addition of lime 

 renders it fit. 



It is noticeable that the temporary hardness of the deep well waters 

 is higher than that of the spring water, where care has been taken. 



Appendix — Form of Questions. 



I.— Position of Well, or Wells with 

 which you are acquainted. 



2. — Approximate height of the same 

 above the mean sea. level. 



3. — Depth from surface to bottom of 

 shaft of well, with diameter. 

 Depth from surface to bottom 

 of bore-hole, with diameter. 



4. — Height at which water stands be- 

 fore and after pumping. Num- 

 ber of hours elapsing before or- 

 dinary level is restored after 

 pumping. 



5. — Quantity capable of being pumped 

 in gallons per day. 



0. — Does the water level vary at dif- 

 ferent seasons of the year, and 

 how ? Has it diminished during 

 the last 10 years ? 



7. — Is the ordinary water lerel ever 

 affected by local rains, and if so, 

 in how short a time ? And how 

 does it stand in regard to the 

 level of the water in the neigh- 

 bouring: streams, or sea ? 



10. 



11 



8. — Analysis of the water, if any 1 Does 

 the water possess any marked 

 peculiarity ! 

 9. — Nature of the rock passed through, 

 including cover of drift, with 

 thicknesses. 

 -Does the cover of drift over the 



rock contain surface springs ? 

 -If so, are they entirely kept out of 

 the well ? 



12. — Are any large faults known to exist 

 close to the well ? 



13. — Were any salt springs or brine wells 

 passed through in making the 

 well? 



14. — Are there any salt springs in the 

 neighbourhood ? 



15. — Have any wells or borings been 

 discontinued in your neigh- 

 bourhood, in consequence of 

 the water being more or less 

 brackish ? If so, if possible, 

 please give section in reply to 

 query No. 9. 



Report of the Committee, consisting of Jas. R. Napier, F.R.S., 

 Sir W. Thomson, F.R.S., W. Froude, F.R.S., J. T. Bottomley, 

 and Osborne Reynolds, F.R.S. (Secretary), appointed to in- 

 vestigate the effect of Propellers on the Steering of Vessels. 



Since the Meeting of the British Association held in Plymouth last year, 

 the Committee have had the satisfaction of receiving reports of the trials 

 of various English and foreign steamers, made by the owners and officers 

 of the steamers, without any further instigation from the Committee than 

 that contained in their circulars. These reports all show that those by 

 whom the trials were made have become convinced of the importance of 



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