814 REPORT— 1895. 



cocks and one without, to which our English Board of Trade has to shut its eyes, 

 as the German standjiipe, from their point of view, is unsafe and ought not to be 

 allowed. 



7. Exjyeriments on the Transfer of Heat through Plates with Variously 



Arranged Surfaces. By William George Walker, M.Inst.M.E., 

 A.M.Inst.C.E. 



The ohject of these experiments is to compare the effects on the transfer of heat 

 of variousl}' arranged surfaces projecting from the primary surface of a plate in 

 contact with steam, air or water. 



Two cylindrical smooth vessels were constructed of exactly similar dimensions, 

 cut from the same brass tube, 6J inches in length and 2Y"'ij inches in diameter, fitted 

 with water-tight lids, through which thermometers were inserted. When filled 

 with water no difference was found to exist between their respective powers to 

 absorb or discharge heat. One of the cylindrical vessels was then fitted with 

 copper ribs 6j inches long, ^ inch wide, -01;^ inch thick, soldered on longitudinally. 

 The ribs were spaced equally round the cylinder and tried as follows: — 



1. Eight external ribs. 



2. Sixteen ribs, eight external and eight internal. 



3. Eight internal ribs. 



The heating of the two cylinders was performed by suspending them in steam 

 from boiling water. The two cylinders to be compared were filled with water, and 

 placed in steam when their temperatures were 65° Fahr. 



The reading of the thermometers, together with the time, was noted simul- 

 taneously at every 10 degrees. The time was taken in seconds by a ship's chrono- 

 meter. When the thermometers became stationary at 210° Fahr. the cylinders 

 were suspended either in air or water and allowed to cool down, the temperatures 

 being noted every 10° Fahr. and the time in seconds. 



The difference between the temperatures of the corresponding plain and ribbed 

 cylinders increased from zero and reached a maximum, after a certain time after 

 which they again closed to equal degrees. 



The ribbed surfaces increased to a considerable extent the rapidity of transfer 

 of heat either when absorbing heat from steam or discharging it into the air. The 

 effect was not so great when cooled in water. In the externally ribbed cylinder 

 the greatest advance in temperature over the corresponding plain one was 18° Fahr., 

 33° Fahr., 8° Fahr., when in contact with steam, air, and water respectively. The 

 addition of the internal ribs to the external ones did not produce much effect. 

 With the internal ribs alone, the rapidity of transfer of heat was increased when 

 cooled in water, but practically no effect was perceived when in steam or air. 



The external ribs were more effectual in discharging heat to the atmosphere 

 than in absorbing it from steam. This difference may be due to the condensed 

 layer of water which was deposited on the surf^ice. 



Coiling wire round was also tried. The temperature of the coiled cylinder fell 

 faster than the corresponding plain one in air, but rose slower in steam — due 

 probably to the condensed layer of water deposited between the wire coils. No 

 difference was noticed when cooled in water. The comparison of rough and 

 smooth surfaces when absorbing heat from steam or discharging it into air or water 

 was also tried. 



8. A New Princijile of Aerial Navigatio7i. By Lieut. B. Baden-Powell. 



It has been the constant desire of inventors to devise some means by which we 

 may be able to navigate the atmosphere. Wings, vertical screws, aeroplanes, 

 have all had their advocates, and great hopes were aroused in the balloon. Many 

 proposals were made for steering this aerial buoy, and sails and rudders were ap- 

 plied to the apparatus, until scientists pointed out that these could be of no avail 



