406 THE SCIENTIFIC PAPERS OF 



construction of the two. I may mention here a case with which 

 I had to deal in a small way a year or two ago. I have at my 

 house in the country a terrace, and beneath that ten-ace a billiard 

 room ; I wanted to lower the terrace six inches and to raise the 

 ceiling of my billiard-room at least a foot. The billiard-room 

 had been constructed according to ordinary practice. I managed, 

 by putting steel girders over this billiard-room (which was about 

 seventeen feet span), by filling in between girder and girder with 

 cement and covering it with the same sheet of lead that had 

 formerly been used, to save the eighteen inches I required. The 

 result was a perfectly dry room of increased loftiness, whereas 

 before I had considerable difficulty in keeping the water out. 

 This simply shows how, by the use of the stronger material, 

 structural advantages, besides saving in cost, may be obtained. 

 But it has also been reproached against iron that it is not fire- 

 proof. I have heard Captain Shaw say he liked houses with 

 wooden beams and columns, because he knew exactly when they 

 would give way, whilst this was not the case with iron. The 

 remark is no doubt the result of very extensive experience, but I 

 expect that it has arisen through the use of cast iron. ISTow cast 

 iron, I should think, is a very unsafe material to be used in archi- 

 tectural structures. You can never know with certainty whether 

 the iron is sound throughout, when put in the shape of a column 

 or girder, or whether there are not unperceived cavities Avithin the 

 shell that make it unsafe. Another danger is that in case of fire 

 cast iron, when heated partially, is apt to crack, and the fire 

 brigade would receive no warning as to when the building would 

 give way. But in using steel a very different condition of things 

 obtains. Steel is produced at the highest temperature attained in 

 the arts, and it sets or solidifies at a temperature far exceeding 

 that reached in a burning house. Therefore, although the struc- 

 ture contains this material in parts where strength and solidity 

 are required, it would be improbable that any portion of the fabric 

 would be heated, in case of conflagration, to a temperature suffi- 

 cient to make it yield on account of that temperature. The 

 temperature would depend upon the amount of combustible 

 material accumulated at any one place, and by the employment of 

 steel instead of wood in the structure the quantity of combustible 

 material would be necessarily much diminished ; it would be 



