LIST OF ILLUSTRATIONS xvii 



FIG. PAGE 



5. Layout of Pennsylvania Avenue, Washington, D. C 69 



6. Layout of street sixty-six feet wide, buildings thirty-five 



feet high 70 



7. Layout of street one hundred and twenty feet wide, build- 



ings sixty-five feet high 71 



8. Single row of trees on narrow street having tall buildings 72 



9. Small trees on a narrow street having tall buildings. ... 73 



10. The disposition of trees at street intersections 78 



11. Young Sugar Maple before being top-pruned 90 



12. Same Sugar Maple after being top-pruned 90 



13. Pin Oak, top-pruned ready for planting 91 



14. Method of placing grill 98 



15. Sectional view and plan of a subirrigation device 99 



16. Sectional view and plan of a subirrigation device 100 



17. A street the trees of which are in need of pruning 113 



18. Transverse section through callus on a horse-chestnut. . 119 



19. Tree with branch to be removed 120 



20. Split caused by improper method of pruning 120 



21. Oriental Plane to be headed back 126 



22. The same Oriental Plane headed back 126 



23. The same Oriental Plane a year after the operation. . . . 127 



24. The same Oriental Plane several years after the operation 127 



25. A dendroscope 129 



26. Combination chisel and hook 132 



27. Method of making tight joints in gas-pipes 144 



28. Method of protecting a branch from abrasion by wire 



cable 148 



29. A "well" constructed about an elm-tree when grade was 



raised 153 



30. Spray nozzles 214 



31. Spray " Ys" 215 



