218 MASSACHUSETTS AGRICULTURE. 



their entire length. Their size will depend on the amount of 

 water they may be expected to carry and this again on the rain- 

 fall that may occur on the area which they drain. Extraordinary 

 showers have occurred of 2" in half an hour but only over a very 

 limited area and 2" in an hour may be taken as a large allow- 

 ance. This is the basis of the Central Park drainage calcula- 

 tions and is larger than usually taken, none too large however 

 for safety. As culverts grow larger and wider with the amount 

 of water they are to pass under the road, they develop finally 

 into 



Bridges. 

 Bridge-building is a life's study, taken by itself, and in some 

 of its parts it is not half appreciated and known as yet among 

 the public. Prominent among these is beauty of design and 

 appropriateness to the situation. There is perhaps nothing else 

 that will so much improve the appearance and attractiveness of 

 a road as a beautiful bridge. So also in cities we find that a 

 street will of its own accord, seemingly, improve in appearance, 

 when a good and handsome bridge has been erected on its line, 

 the owners and builders of the adjoining buildings taking the 

 bridge for their pattern and model. Nor must it be supposed 

 that a handsome bridge must necessarily cost more than an in- 

 appropriate or homely, uncouth structure ; it need never be the 

 case. Very often the chief beauty of a structure lies in the fact 

 of its carrying the most with the least expenditure of material. 

 No one bridge is proper in every situation and herein are many 

 mistakes made. The correct way to build a good bridge, is the 

 same or a similar way to that followed in first-class buildings, 

 namely, to have plans drawn for the same and receive estimates 

 and offers to build according to these plans. It is not well to 

 allow the offices of designer, superintendent and contractor to 

 be united in one person or firm, and is expecting too much from 

 human nature. 



Making the Road Surface. 

 There are two subordinate kinds of road surface, if the term 

 road can properly be applied to them, namely, that of foot and 

 riding paths ; these may be disposed of first, before proceeding 

 to the more important consideration of the road surfaces proper, 

 those used by vehicles of all descriptions. 



