164? Analysis of Scientific Books and Memoirs. 



6. An Improved method of working Water Wheels. By Mr William 



Moult. 



This method, which is secured by patent, consists in immersing a bucket- 

 wheel in water, and in throwing a current of air under the buckets at 

 the lower part of the wheel, for the purpose of displacing the water and 

 filling them with air. One side of the wheel being thus rendered specifi- 

 cally lighter than the other, it revolves. — See Newton's Journal of Arts, 

 Sept. 1826, p. 76, where this contrivance is more fully explained. 



Art. XXVII.— ANALYSIS OF SCIENTIFIC BOOKS AND ME- 

 MOIRS. 



I. — Journal of a Third Voyage for the Discovery of a North-west Passage 

 from the Atlantic to the Pacific, performed in the years 1824-5, in his 

 Majesty's Ships Hecla and Fury, under the orders of Captain William 

 Edward Parry, R. N. F. R. S. 1826. 4to. 



In a preceding article of this work we have already made our readers 

 acquainted with the leading particulars of the narrative of this expedition. 

 We shall therefore not touch again upon this part of Captain Parry's work, 

 but shall proceed to the more appropriate object of this article, viz. to give 

 an analysis of the scientific results obtained by the expedition. 



1. Magnetical Observations. 



After the ships were secured, and the observatory erected on shore, Cap- 

 tain Parry directed his attention in an especial manner to magnetical in- 

 quiries. The first observations on the magnetic needle on the arrival at 

 Port Bowen, discovered to them the interesting fact of an increase in the 

 variation since 1819, amounting to about 9°, viz. from 114° to 123°. To 

 the northward Lieutenant Sherer found the increase to be only 5° A3, and 

 Lieutenant Ross to be southward only 1°15. By using needles delicately 

 suspended, he discovered a very remarkable diurnal variation. The maxi- 

 mum westerly variation was observed to occur between 10 h a. m. and l h 

 r. m., and the minimum betwen 8 h p. m. and 2 h a. m. The exact time of 

 the maximum, as deduced from a mean of 120 days, was ll h 49' a. m. and 

 that of the minimum 10 h 1' p. m. The amount of the diurnal variation 

 was seldom less than l£° or 2°, and it sometimes amounted to 5°, 6°, and 

 even to 7°. 



Captain Parry likewise discovered a diurnal change in the magnetic in- 

 tensity, which, excepting occasional anomalies, exhibited an increaseof inten- 

 sity from the morning to the afternoon, and a decrease from the afternoon 

 to the morning. " It also appeared that the sun, and, as we had reason to 

 believe, the relative position of the sun and moon with reference to the 

 magnetic sphere, had a considerable influence both on the intensity and di- 

 urnal vnriation." 



In n peating the experiments of Messrs Barlow and Christie on a needle 



