100 REPORT — 1844. 



quence of Me. Scott Russell's paper on the subject, he hail been enabled to make in 

 the defective arrangement of the Court House at Cork. By adapting Mr. Russell's 

 general principle to this particular case, he had succeeded in rendering the feeblest 

 voice effectively heard. 



On the Collection of Water for the Supply of Towns. -% John Batem an, C.E. 

 Mr.Bateman isof opinion that one-half or three-fourthsof the rain is allowed to waste 

 away, and often to do great damage, and suggests that it should be collected in large 

 reservoirs and conveyed thence to towns in the locality*. 



071 the CEconomy of Artificial Light for Preserving Sight. 

 By I. Hawkins, C.E. 



Few were aware, he said, of the injury inflicted on the sight by too much or too little 

 light, and by a sudden transition from gloom to light. He had tried several experiments 

 with a view to procure a light of a medium description. He commenced with two 

 common candles of eight to the pound, alternately snuffing and leaving them unsnuffed, 

 and measuring the intensity of the light by the shadows on the walls. The result of 

 this experiment was, that he found that the candle well-snuffed gave eight times the 

 liffht of that which was unsnuffed. He then proceeded to a process of weighing, and 

 found that one pound of the snuffed candles gave as much light as nine pounds of the 

 unsnuffed candles. With regard to Palmer's and the common dip, he found that a 

 pound and a quarter of the latter, costing 5\d., when well-snuffed, was equal to one 

 pound of Palmer's, costing G\d.; but when the same candle was not snufled oftener 

 than about every ten minutes, it took four to be equal to Palmer's; and, when un- 

 snuffed altogether, it required eleven pounds to be equal to one pound. After 

 alluding to further experiments with candies, and also with oils, he concluded by re- 

 commending the self-snuffing candle in preference to oil-lamps. 



On a new Process of Magnetic Manipulation, with its Effects on Hard Steel 



and Cast Iron. By W. Scoresby, D.D., F.R.S., Lond. ^- Edin., Member 



of the Institute of France. 



During two or three sessions I have had the honour of bringing before the Section, 

 the progressive results obtained in the course of a long series of investigations on the 

 magnetic phaenomena exhibited by steel plates and bars of various qualities and 

 degrees of hardness. In a work recently published, entitled ' Magnetical Investiga- 

 tions,' comprising a detailed account of the researches referred to, it has been shown 

 that no general rule could be given for the construction of magnets, as to the best 

 denomination of steel or degree of hardness ; but that the variations in the masses and 

 proportions, as well as in the forms in magnets, require, beyond certain extents of 

 difference, a different rule. A similar difficulty, in practical magnetics, is found in 

 the determination of a rule or process for the magnetising of bars or plates, under 

 varieties of condition as to mass, proportions and hardness. Two processes, indeed, 

 described in Part I. of the ' Magnetical Investigations,' are most extensively applicable 

 (if the developing or induction magnets be sufficiently powerful) for straight-bar 

 magnets of almost all varieties of mass and temper, or hardness. These processes, 

 modified as required by the peculiarity of figure in horse-shoe magnets, are likewise 

 very effective for this description of magnets of the qualities ordinarily constructed. 

 Neither of the processes, however, nor any process that I have seen described, is 

 foun^ to be constantly effective in the case of thin hard bars of the horses-shoe form. 

 Where the thinness and hardness are extreme, the effectiveness of the usual pro- 

 cesses are most liable to fail. 



The uncertainty of the result, with these most usual methods, induced me to try 

 other processes, suggested by the principles previously investigated. But none of the 

 known processes, as appeared from the irregular application of the magnetical forces 

 in the course of the manipulations with a horse-shoe magnet, were satisfactory, 



• On this subject, Mr. Bateman has undertaken to present a Report to the next Meeting. 



