CHS) 



or contraction has gone on to a slight extent only, and has 

 proved not nearly as great a charge for maintenance as it 

 was supposed it would be. An unprotected blast of rock, 

 just east of the eastern end, fired in August by a foreman in 

 the employ of the contractor engaged in grading caused 

 breakage which cost the contractor over $150 to repair; this 

 is the only accident worth recording. The houses have been 

 repainted throughout on the outside, and nearly throughout 

 on the inside. A few minor defects in the roofs, causing 

 leakage in heavy storms, have been mainly remedied, and I 

 have recently accepted an unsolicited offer by Hitchings & 

 Company, the builders of the roofs, to modify, at their own 

 expense, the construction at the ridges of the lower houses, 

 looking toward a complete correction of this defect, which 

 has, however, not been of a serious character. The heating 

 of these buildings has been easily accomplished by the radi- 

 ating coils first installed, these having proven ample for the 

 purpose in the coldest weather ; from the exposed position of 

 the houses this has, however, only been accomplished by the 

 burning of a very large amount of coal. The trouble from 

 gases emanating from the trenches alluded to in my last 

 annual report has not again been experienced ; it was ap- 

 parently referable to volatile matter contained in the insulat- 

 ing covering of the steam mains. 



After a series of observations with hygrometers and ther- 

 mometers in all the houses taken at intervals of two hours 

 from September, 1900, to May, 1901, in order to ascertain the 

 desirable and practicable relations of temperature and hu- 

 midity to establish for the different parts of the system in re- 

 lation to the plant collections and to external light, a method 

 of shading by a combination of stippling the inner surface 

 of the glass, and by movable shades was adopted. It was 

 necessary to devise this so as to make it practicable to extend 

 it, without loss of work, to the additional houses, the con- 

 struction of which was commenced at that time. The roofs 

 and vertical sides of some of the houses were stippled, using 

 a mixture of linseed oil and white-lead, determined for den- 



