290 



SCIENCE OF GARDENING. 



Part II. 



1456. Garden-ladders are of three species. 



1457. The common ivall-tree ladder differs from those used in other arts in having two 

 pieces of ten or twelve inches in length, projecting at right angles from the upper end, the 

 use of which is to avoid injuring the trees, by keeping the top of the ladder at a small dis- 

 tance from the wall, and thus admit of the operation of nailing, as well there as elsewhere. 



1458. The orchard-ladder consists of a frame on low wheels, as a basis for several lad- 

 ders which fit into each other, and are capable of being hoisted up by machinery so as a 

 person near the extremity of the ladder may have access to any part of a tree with con- 

 venience, either to prune it or gather the fruit. 



1459. The three-styled, forked, and double ladders {fig. 206. a, b, c) are also well adapted 

 for the ordinary purposes of gathering fruit or pruning. 



206 



1460. The rule-joint ladder (fig. 207.) is used for working on curvilinear roofs either 

 of glass, or domes of lead, stone, &c. which require panes renewed or trees nailed. 

 Each step or foot-board, has what is called a stop, to prevent the feet from breaking the 

 glass, and at every joint is a moveable foot to project in the case of training trees on such 

 surfaces, in order that their leaves, &c. may not be injured. Such ladders are particularly 

 useful for repairing curvilinear hot-house roofs. 



208 



1461. The step-ladder (fig. 20S.), instead of round rods on which to place the feet, has 

 steps or boards, an improvement essentially necessary, where much work is to be done, 

 because less fatiguing to the feet. Such ladders have a back or fulcrum by which they 

 stand independently of any other object, and which is removeable at pleasure by drawing 

 out an iron bolt. 



