April 18, 1865. ] 



JOURNAL OF HORTICULTUKE AND COTTAGE OARDENEK. 



301 



WEEKLY CALENDAR. 



M'ntb 



Day 

 of 



Week. 



.iPRlL 18-24, 1865. 



Aver-iee Temperature 

 near Loudon. 



Rain in 



last 

 38 years. 



Sim 

 Rises. 



Sun 

 Sets. 



Moon 



Rises. 



Moon 

 Sets. 



Moon's 

 Age. 



Clock 



■ after 



Sun. 



Day oJ 

 Year. 









Day. 



Niffht. 



Mean. 



Days. 



m. h 



m. \i. 



ra. h. 



m. h. 





m. fl 





18 



To 



Easter Tcesdat. 



60.3 



33.8 



48.1 



15 



Oaf 5 



59af0 



n 1 



13 10 



«: 



44 



108 



19 



W 



Apole (lowers. 



B0.3 



34.9 



47.6 



8 



58 4 



7 



37 I 



22 11 



2i 



58 



1U9 



20 



Tu 



OsHp flowers. 



61.8 



34.7 



4'!. i 



14 



56 4 



2 7 



12 2 



after. 



24 



1 11 



110 



21 



F 



Sun's rteclination 11° 33' N. 



60.7 



37.3 



49.0 



14 



53 4 



4 7 



41 2 



53 1 



25 



I 23 



111 



W 



S 



Beech foliates. 



60.4 



37.5 



48.9 



20 



51 4 



6 7 



10 3 



14 3 



2! 



I 38 



112 



as 



Sun 



1st, or Low Sunday. 



60.3 



36.7 



48.5 



20 



49 4 



7 7 



38 3 



35 4 



27 



1 47 



113 



24 



H 



Butter-burr tiowers. 



60.2 



35.7 



43.0 



15 



47 4 



9 7 



9 4 



51 6 ^ 23 



1 SS 



114 



From obsprvations taken near London durine the last thirtv-eiyht ve* 



s, the average <\-i 



y teinperature of 



the week is eo.6° 



and its 



niffht 



temperature 



36.1'. The greatest hent was 77° 



on the 19th, ISoJ 



; and tb 



e lowest 



cold, 18' 



, on the 24lh, 1854. The greatest 



all of raiu was | 



0.60 Inch. 



















1 



GLASS FOE HOETICULTFEAL PUEPOSES. 







i?^ 



>^4-!^ AM glad that Mr. Pear- 

 son lias called at- 

 tention to the in- 

 difterent quality 

 of sheet glass, and 

 I can confirm all 

 he says respecting 

 it, as it is certainly 

 not so good as it 

 ought to be, and, 

 I think, might be. It must, however, 

 be borne in mind that the competition 

 for cheapness has, in this case, as in 

 many others, brought a rery inferior 

 article into general use ; and it is to be 

 feared that much of what is rejected for dwelling-house 

 windows is worked into horticultural buildings. The 

 remedy, however, lies, to a certain extent, in the hand of 

 the builder, and, by insisting on only good clear glass, 

 he may obviate much of the annoyance caused by break- 

 ages from natural causes, provided the glass be also well 

 tempered, and in other respects good. Sheet glass, how- 

 ever, has some defects in its manufacture which it is 

 difficult to rectify ; and I very much question whether 

 any of it is as strong as the old crown glass of the same 

 thickness, but very little of the latter was made any- 

 thing approaching the thickness that is now given to 

 sheet glass in most cases ; and glaziers have some excuse 

 for clinging so pertinaciously to the old kind whenever 

 it can be used to advantage. The subject is well worthy 

 of a discussion in the pages of The JorEXAL of Hokti- 

 CTILTUEE, and I hope to have the opinion of some of the 

 glass manufacturers. In my own case I may say that, 

 in aU fixed glazing, I have for several years advocated 

 ■ the use of sheet glass of 26 ozs. to the foot ; and if this 

 be good, and in squares not exceeding 2 superficial feet, 

 the breakage by natural causes ought not to be much. 

 I attribute much of the damage done to glass in frosty, 

 and even in hot weather, to such glass being, as Mr. 

 Pearson says, "badly annealed;" and, in some cases 

 that have come under my eye, the worst kind in this 

 respect is the Belgian glass, which, on account of its 

 cheapness, has been largely imported into our markets. 

 To all appearance this glass is equal, or perhaps superior, 

 to our own of the like kind ; but it certainly is more 

 liable to break, and consequently causes great annoy- 

 ance. 



I should much like if some one conversant with the 

 manufactui-e of glass would give us the respective amount 

 of elasticity in Belgian and British sheet glass of the 

 kinds usually employed in horticultural buildings ; for, 

 however small may be the elasticity of either, there is no 

 question that the one which possesses the most is least 

 likely to be broken, more especially from natui-al causes. 

 I am certainly of opinion that home-made glass is less 

 brittle than that from the continent ; but as to the causes 

 which render it so I can give no opinion. Perhaps the 

 No. 212.— Toi, Till, New Seiue£. 



raw material may be a better, or. as Mr. Pearson says, 

 the annealing process may be better understood or 

 cari-ied out ; while, on the other hand, Belgian glass 

 presents quite as even a snrfaco, and is, perhaps, more 

 white than the same kind made at home. I have oc- 

 casionally made some experiments with long narrow 

 strips of glass bj' bending them almost to the breaking 

 point, and a piece 2 feet long will bend considerably. 

 What opportunities I have had of trying both kinds of 

 glass lead me to give the preference to the home-made 

 article for that quality which may be designated tough- 

 ness. I may, however, be mistaken, and would much 

 like to hear the opinion of others on this matter. I may 

 also remark that the stouter kinds of glass seem to resist 

 the action of frost better than the old thin crown glass, 

 but there are other causes of breakage which are not so 

 easily accounted for. A few remarks on these may, 

 perhaps, throw some light on the subject. 



In glazing with large squares, or rather with long ones, 

 it is cot unusual for glaziers to fasten them in their place 

 with small nails, and, if there should be a bend in the glass, 

 to let the nail press that part, so as to have it nearer a level 

 than it was before ; the result often is that, in a day or 

 two afterwards, the square is broken. jSTow, how is this 

 to be accounted for, as no fracture was visible at the time 

 the square of glass was fixed in its place ? but such cases 

 are of frequent occurrence. The only theory seems to 

 be that change of temperature acts on the glass, and 

 compels it to disengage itself, or pai'tiaUy so, and when 

 the resistance of the nail cannot be overcome a fracture 

 is the result, and I have seen the same thing occur after 

 a cold night ; but the breakages attributable to this 

 cause are few compared with those which arise from the 

 action of heat and cold in another way. One of the 

 most common of these is the freezing of the moisture in 

 the overlaps of the roof, which, in the case of thin glass, 

 causes great destruction, more especially if such over- 

 laps are wide, and admit of a large amount of moisture 

 being collected, and, on its expanding with frost, a lon- 

 gitudiual crack is formed in one of the squares ; this, 

 though almost imperceptible at first, only requires a very 

 slight pressure of the finger to makejt run a long distance 

 up the square. This is more especially the case with 

 the old crown glass ; but slieet glass is liable to the same 

 evil, though to a less extent, in conseqitence of its being 

 thicker, and lying more Hatl3' on its bed. Tightness in 

 the glazing-bar may. perhaps, at times occasion a break- 

 age, but I do not til 'Ilk this is often the case ; neither do 

 I consider that the expansion and contraction of metallic 

 bars is to be blamed for the loss of glass so often 

 attributed to that cause. I am more disposed to think 

 that vibration has something to do with the breakage ; 

 and in lightly-constructed iron houses the loss is often 

 considerable, especially if the squares are small, and 

 the glass thin. Hailstorms are an exceptional cause of 

 damage, which it would be well to guard against by 

 only using thick glass ; but the loss from such causes is 

 only likely to occur once or so in a lifetime, but when, 

 they do they are very disastrous. I have seen upwards 

 No. S64.-VOL. XXXIII., Old Series^ 



