TRANSACTIONS OF THE SECTIONS. 27 



bars of cast iron, as well as of wrought iron ; but he was not prepared to give the 

 final results. 



It was found that in all cases where a strain had been applied to a body, it showed 

 for some time afterwards a tendency to return towards its original form, though it 

 never would be able to arrive at it. This was particularly evident for a few minutes 

 at first, and on that account the sets were usually taken twice or more, as at the ex- 

 piration of one minute and five minutes, and sometimes half an hour after unloading ; 

 but after five minutes they seldom altered much. 



In all materials, the sets produced by the smallest weights tried, seemed to be 

 nearly in the ratio of the weights ; but as the small friction of the apparatus would 

 make a sensible addition to the set due to the material from such small strains, he 

 drew no conclusions from the fact. 



Mr. Whitworth exhibited an instrument for measuring bodies to a very minute de- 

 gree of accuracy. It consisted of a strong frame of cast iron, at the opposite extre- 

 mities of which were two highly finished steel cylinders, which traversed longitudi- 

 nally by the action of screws one-twentieth of an inch in the thread ; these screws 

 were worked by two wheels, placed at opposite extremities of the frame, the larger 

 of which had its circumference divided into five hundred equal parts ; the ends of 

 the cylinders, at the places were they approached each other, were reduced to about a 

 quarter of an inch, and their hemispherical ends were highly polished. To measure 

 with this instrument, the large circle was brought to its zero, and the body to be 

 measured, being placed between the cylinders, the small circle was turned until the 

 two cylinders touched the opposite sides of the body, which being removed, and the 

 large circle turned until the ends of the two cylinders were brought to touch the 

 turns and parts of a turn required for this, it gave the breadth of the body which had 

 been interposed to the ten-thousandth part of an inch, and since the one-tenth of 

 one of the divisions could be readily estimated, the size of the body could be thus 

 estimated easily to the j^j^^th part of an inch. Mr. Whitworth stated, that in the 

 accuracy required in modern workshops, in fitting the parts of tools and machines, 

 the two-foot rule heretofore in use is not by any means accurate enough ; his object 

 was to furnish ordinary mechanics with an instrument which, while it afforded very 

 accurate indications, was yet not very liable to be deranged by the rough handling 

 of the workshop ; and he conceived this instrument secured those advantages. It 

 surprised himself to find how very minute a portion of space could be by it, as it 

 were, felt. By it the difference of the diameters of two hairs could be rendered quite 

 palpable. 



Communications from Norway, presented by John Lee, LL.D., F.R.A.S. 



A paper by J. R. Crowe, Esq., Consul- General of Her Britannic Majesty for Nor- 

 way, dated Christiana, 29th May 1844, entitled, ' General Observations on the Cli- 

 mate of Norway and Finmark, with some remarks on the Geography, Geology and 

 Agriculture.' 



Also, a table of meteorological observations, taken at Christiana, north latitude 

 59° 54' 1", east longitude 10° 45', during the year 1843, and the barometrical and 

 thermometrical means for each month. 



A letter, dated Alten Observatory, 20th April 1844, from J. H. Grewe, Esq., de- 

 tailing the difficulties which he had to encounter on ascending the mountain called 

 Storvandofjeld, on the 1st December 1843, to fix a minimum thermometer on its 

 apex, and of his second expedition on the 17th of April 1844 to examine it, and 

 bring it down to Alten ; the lowest degree of cold on the top of the mountain 

 during the winter having been 35° longitude, and the lowest degree at Alten 27°, a 

 difference of 8° between the two places. 



Also an account of a fine parhelion which he beheld at 5'' 50™ a.m. at a height of 

 about 1500 feet, with a drawing. 



A paper by John Francis Cole, Esq., Member of the Literary and Astronomical 

 Society of Alten, on the Aurora Borealis, as seen at that place, and which has been 

 drawn up from a series of observations. 



