.No. 104.] 199 



country occupied by these have been roughly traced in different col- 

 ors upon the map accompanying this report, so far as it covers the 

 ground. I shall hope to have an opportunity of completing this 

 work, and presenting such a map as will illustrate the important 

 points relating to the subject of materials for construction and orna- 

 mentation, 



y. 



On the Selection of Building Stones, and the Causes of their 



Decay. 



In the selection af building stones for the exterior walls of a build- 

 ing, color, texture, and durahility^xQ, objects of the first importance; 

 and all of these ought to be combined, to render the structure per- 

 fect. Too little attention has been given to the subject of building 

 stones; while on the one hand we are largely using a brown stone, 

 which gives a sombre, cheerless aspect to the structure, the opposite 

 extreme has been sought in the white marble, or that which is more 

 nearly white in color. In contrast with these we have the red glar- 

 ing color of brick; and it is only partially that this offensive aspect 

 is palliated by painting of neutral tints. In a few eastern cities and 

 towns we find the light gray granites now used in preference to the 

 brown freestone, the white marble, or the dark granite, which have 

 been much in use in past years. 



No one can fail to experience the sensation of relief afforded by 

 the structures, of light-colored granites in the city of Boston, or 

 those of the buff" or dove-colored limestone in the city of Chicago, 

 or of tlie light gray freestone of many buildings in Cleveland and 

 other places and of the buff"-colored brick of Milwaukee. In these 

 cases we have not the excessive reflection of light, or the glare which 

 comes from white buildings whether of marble or of painted brick; 

 nor the sombre, cheerless expression of the darker stone, caused by 

 its great absorption of light. It is only necessary to consider the ef- 

 fects produced by the structures of these different materials upon one's 

 own sensation, in order to determine what are the most agreeable 

 tints, or those which please the eye and produce a cheerful im- 

 pression upon the mind. 



In the majority of structures, the necessities of locality, cheap- 

 ness, or other causes compel the erection of structures from ma- 

 terials most accessible ; but these considerations are not imperative 

 in the cases of an important public building. 



In many cases where the rock is homogeneous throughout and 

 the color uniform and satisfactory, it is only to be inquired whether 

 the coloring material is such as will produce decay or disintegration 

 of the particles. When the general color is produced by the aggre- 

 gation of different materials of distinct coloration, the character of 

 each one is to be considei-ed, and its effect upon the whole ; and it 

 is important to have such material comparatively fine-grained, and 



