probably been hit on, without consideration of the principle on which it is founded. If this reasoning be correct, it is superior to every other form, and the only improvement it is capable of, is by considering and calculating the proportion of the cone, as it is too much to suppose that the best modification of it has been hit off at the first heat of the invention or application. I cannot help thinking that Mr. Rogers overrates the effect of friction in fixing his level, especially when you deduct the weight of the column to be raised perpendicularly to the upper or flowing point. However, it cannot be of very much importance either way. My observation only went to guard against the effects of the somewhat loose manner in which it was treated in his first paper. In his courteous answer to my last note, Mr. Rogers has mistaken my meaning, which is of itself of little importance; but, as it may be of very grave consequence in bringing his excellent plan into general use, I will endeavour to correct it. The words of Mr. Rogers are: "With respect to the given quantity of water which any boiler would heat to boiling, a little reflection will, I think, show that it is a question not admitting a definite answer, and that, if answered, could lead to no practical result.' I perfectly agree with Mr. Rogers, that such an enquiry would be loss of time, but my meaning was wholly different. So far from wishing to ascertain the quantity of water each boiler would boil, my object is to ascertain what quantity each would heat to 200°, or thereabouts, BOILING being expressly guarded against in my view of the case. It is very clear that there must be a limit to the capacity of eachsized boiler; and, assuming 200° as the best point of comparison, there would be no great difficulty in ascertaining how much each size would manage, when, by measuring the cooling surface of the house, it could be easily put in the power of any amateur or working gardener to estimate the size his house would require. This very important point should be attended to either by the inventor or the manufacturer, and the hope of inducing them to do so, and consequently to enhance the value of this simple and excellent invention to the horticultural public, by extending its use, is the sole reason of my recurring to the subject. I perfectly agree as to the greater friction of 2-inch pipes; on which account, as well as their being liable to choke from impurities of water, being more subject to defects in the casting, and the economy which appears to be their sole recommendation being trifling, they should probably be banished from any houses of importance. Of course the friction is very much augmented by elbows and turns, especially by descents to cross footways and the like.-W. The Black Eagle Cherry.—I see that the Black Eagle Cherry, to which I gave a good character at p. 264., is denounced in strong terms by T. R. of Liverpool, at p. 375. The size of fruits must of course be estimated by comparison with others of the same class, and according to this rule I judged the cherry in question, making it a good-sized (that is, a middle-sized) fruit, intermediate between the small kinds, such as the Corone, and the large, like the Bigarreau. By referring to the Horticultural Society's Fruit Catalogue, I find my estimate of this cherry confirmed, for it is there classed with the May Duke, Kentish, and others, as a second or middle-sized fruit; it is, moreover, stated to be of the first quality, and as the account of its quality there given is the result of perhaps as much experience as T. R. can boast, many persons will have the hardihood to consider the author of that work the better authority of the two. I have myself grown the Black Eagle, and therefore am enabled flatly to contradict this libeller of cherries, who says that " a poorer, more vapid fruit was never produced." Either T. R. does not know the Black Eagle, or the inferiority of his fruit is the result of some defect in soil, situation, or management.-J. B. W. July 8. THE GARDENER'S MAGAZINE, OCTOBER, 1840. ORIGINAL COMMUNICATIONS. ART. I. The Derby Arboretum, founded by Joseph Strutt, Esq.: containing a Catalogue of the Trees and Shrubs, the History and Object of its Formation, the Reasons for the main Features of the Plan, and Directions for its future Management. By the CON DUCTOR. I. CATALOGUE OF THE TREES AND SHRUBS. THE numbers which precede the names in this catalogue are those which precede the names on the brick tallies (fig. 51.), and their object is to facilitate the discovery of any species or variety which it may be wished to examine. The place of any plant in the Arboretum may be readily found by looking to the place of the nearest number in the ground plan, which forms the engraving fig. 52. For example, if it is desired to find the plant marked No. 26., find Nos. 20. and 30. on the plan, and No. 26. will be found between them in the grounds. The numbers and names, which commence with the plants of Ranunculaceæ, begin at the right hand on entering the garden, are continued round it, and end with No. 802. on the left hand. Several plants have numbers followed by letters, as 16a., 16b., 16c., &c. ; these merely show additions that were made after the first numeration was completed. These additions were made, partly because some plants were added which were at first thought too tender, and partly because some were obtained from the Horticultural Society's Garden, which it was thought could not be procured. On the cards contained on the brick tallies (fig. 51.), the native country, 1840. Ост. M M 53 1. year of introduction, and height of the plant in its native country, are always given, as in fig. 53., and therefore these are not repeated in this enumeration. An enlarged catalogue, containing descriptive or historical notices of all the remarkable species, is printed as a pamphlet of five or six sheets, and sold by the curator of the Arboretum; and in the public room of the curator's lodge a copy of the Arboretum Britannicum is kept for the use of gardeners and botanists FRANCE. who may wish to refer to it. The prices of the species, with a few CLEMATIS FLA'MMULA. THE INFLAMMATORY-JUICED exceptions, will be found in the list given in p. 73. Ranunculacea. 1. to 11. CLEMATIS L. 1. Flámmula L. 2. orientális L. 3. Vitálba L. 4 virginiana L. 6. flórida Thunb. 8. Viticélla cærulea 9. Viticélla purpùrea Hort. 10. Viticélla múltiplex 11. montàna Ham. 12. alpina L. Pæoniàceæ. 14. and 15. PEO`NIA L. 15. Moútan Bánksi And. 16c. grandiflòra exoni- 16d. glaúca L. 16f. tripétala L. 18. (a.) cordàta Michx. 19. conspicua Salisb. 21. MENISPERMUM ca- Berberàceæ. 22. to 31a. BERBERIS 22. vulgàris L. 24. canadénsis Mill. 32. Aquifolium Nutt. Cistacea. 336. to 37. CI'STUS L. 15 FT. 38. to 49. HELIANTHEMUM Tourn. 38. cànum Dunal. 39. cròceum Pers. 40. vulgàre Gært. 41. surrejànum Mill. 42. macránthum Swt. 43. macránthum flòre plèno Hort. 44. rhodánthum Dunal. 45. canéscens Swt. 46. mutábile Pers. 47. sulphureum Willd. 48. venústum Swt. 49. Milleri Swt. Malvacea. 50. to 54. HIBISCUS L. 51. syriacus flòre varie- 55. to 61. TILIA L. Hort. 59. europæ'a aurea Hort. 59a. europ. álba Waldst. et Kit. 60. americàna L. Ternströmiàceæ. 62. MALACHODENDRON 626. GORDO`NIA pubés- Hypericàcea. 63. to 66. HYPERICUM 63. elatum Ait. 66a. officinale Allioni. Aceràceæ. 67. to 86. ACER L. 73. platanoìdes lacini- variegata Hort. 77. Pseudo-Plátanus álbo variegata 78. Pseudo-Plátanus purpurea Hort. 89. to 95. E'SCULUS L. 99. flàva Dec. Sapindacea. 105. KÖLREUTE`RIA pa- Vitàceæ. 106. to 109. VITIS L. 107. Labrusca L. Xanthoxylàceæ. 113. XANTHOXYLUM L. 115. AILANTUs glandu- Coriacea. 116. CORIA RIA myrtifo- Staphyleàceæ. 117. and 118. STAPHY- 1246. japonicus Hort. Aquifoliacea. 126. to 137a. I`LEX L. 128. Aquifolium fèrox 129. Aquifolium senés- marginàtum Hrt. píctum Hort. argenteum Hort. aúreum Hort. L. 138. decíduus Dec. 139. verticillàtus L. |