July 28, 1863. ] 



JOUKNAL OF HORTICULTURE AND COTTAGE GARDENER. 



61 



WEEKLY CALENDAR- 



JULy.28— AUGUST 3, 1S63. 



W. Forsyth, jun., died, 183: 



Fennel flowers. 



Sea Lavender flowers. 



Flax flowers. 



Lammas Day. 



9 Sl-kuat after Tri.mty. 



Saffron Crocus flowers. 



Average Teraperatnve i'^'^'", '° 

 near London. 'Myt^,,, 



Day. 

 76,0 

 75.6 

 74.8 

 74.9 

 75 9 

 75.8 

 74.5 



Night. 

 52.2 

 50.8 

 51.3 

 51.1 

 51.2 

 52.5 

 51.4 



Mean, 

 64.1 

 63.2 

 63.0 

 63.0 

 63.6 

 64.1 

 68.0 



Days. 

 19 

 15 

 16 

 14 

 17 

 17 

 19 



Sun 



Rises. 



h. 

 19af 4 



Sun 

 Sets. 



m. h, 

 54af7 

 52 7 



Moon 

 Kises, 



m. h. 

 12a 6 

 55 6 



Moon 



Sets. 



m. h. 

 34af 1 



49 3 



13 4 



39 5 



2 7 



23 8 



43 9 



Moon's 



Age. 



Clock 

 before 

 Sun. 



13 

 14 

 O 



16 

 17 

 18 

 19 



m, s. 



6 13 



6 12 



6 10 



6 7 



6 4 



6 



6 56 



Dayof 



Year. 



20» 



2ie. 



211, 

 212 

 213 

 214 

 21S 



From observations taken near London during the last thirty-six years, the average day temperature of the week is 75.4°, and its niglit 

 temperature 51.5°. The greatest heat was 92", on the let, 1846, and 2nd, 1856 ; and the lowest cold, 34°, on the l»t, 1858. The greatest 

 fall of raiu was 1.39 inch. 



BOILEKS. 



N constructing a hot- 

 water apparatus, a 

 good boiler is tlie 

 first coasideration. 



In my opinion the 

 merits of a boiler 

 for horticultural pur- 

 poses, should be 

 measured in the following 

 order: — 1st, It should present 

 a large surface to the direct 

 action of the fire. 2nd, It 

 ought to need little water to 

 fill it. 3rd, It should be made of a material not likely to 

 wear out soon. 4th, The base or bottom should be 

 .double the width of the top. 5th, It should be so con- 

 structed that it will not be soon choked with soot, and 

 should be easdy cleaned out. 6th, It should be of easy 

 access for being repaii'ed. 7th, It should h«at quickly. 

 8th, It should be easy of management. 9tb, Its furnace 

 should burn any description of fuel. 10th, It should 

 require but little attention. 11th, It should be capable 

 of being regulated so as to heat a little as well as a large 

 amount of piping without any waste of fuel. 12th, Pro- 

 vision should be made to clean the inside of th« boiler, 

 to keep it clear of sediment. 



Some of the points named convey their own meaning, 

 but a few remai'ks on each may not be out of place. 



On point 1st, I may observe that the parts immediately 

 over the fire receive the greatest heat, and those parts 

 ought to be stronger than the rest ; but whether the 

 expected saving likely to accrue from thus providing 

 against wear and tear, would more than balance the 

 increased slowness of heating, has yet, to be proved. 

 Water in a tin saucepan is sooner heated to a given point 

 than in a copper one ; brass is some time longer in heating, 

 and an iron pan longer still : therefore, it is only common 

 sense to imagine a boiler side or bottom half an inch 

 thick would heat the water in contact with it quicker, 

 and a greater quantity, than one double that thickness. 

 I dispute the claims of a boiler to preference because it 

 exposes a large amount of surface to the action of the 

 fire. It would be well to discriminate between direct 

 and indirect action. The parts immediately over the fire 

 I think may be considered direct, and those receiving 

 the flame or heat after it has been in contact with 

 another part of the boUer indirect. The one has double 

 the heating power of the other. The fire in the first place 

 would melt brass (1869°), whilst in the other it would 

 not melt lead (594°). Water, however, cannot be heated 

 to more than 212°, a few degrees more or less according 

 to the pressure of the atmosphere ; yet it does not follow 

 that a material capable of being heated by a common fire 

 to a temperature of 1141° (DanieU), will not boil more 

 water in a given time than the same material at half the 

 temperature. A boiler, therefore, exposing 10 feet of 

 direct, and 20 feet of indirect surface to the action of the 

 No. 122— Vol. V., New Sekkis. 



fire, will not heat more water to a given temperature than 

 one with 15 feet of surface directly exposed to the action 

 of the fire. It does not follow that a saddle boiler with 

 12 feet of direct, and the same quantity of indirect 

 surface, wiU heat as much surface as a tubular boiler with 

 12 feet of direct, and 48 feet of indirect. The tubular in 

 this case would heat one-third more water than the 

 saddle boiler ; but a saddle boiler with 30 feet of direct, 

 and the same quantity of indirect surface, would heat 

 more water to 212° than a tubular boUer with 10 feet 

 immediately over the fire (directly exposed), and 50 feet 

 of indirect surface. 



On the 2nd point I need not comment, for it will be 

 evident that a boiler holding but twenty gallons of 

 water will be sooner heated than one holding forty gallons. 

 Large boilers holding a large quantity of water must be 

 wide inside, from one side to the other, but a boiler 

 holding but little water must have its parts narrow. 

 On this point I need not further enlarge, beyond stating 

 that the heating capabilities of a boiler are nearly as 

 much dependant on the water it contains as on the 

 isurface exposed to the action of the fire. A boiler hold- 

 ing forty gallons of water cannot be so economically 

 heated as a boiler liolding but twenty gallons, both 

 having the same amount of heating surface. The former 

 gives heat where it is not wanted, in the boOer, the othor 

 in the pipes within the house required to be heated. 



I ma}' observe on the 3rd point, that the best metal 

 adapted for boilers appears to me to be cast iron. Water 

 prevents metals from being heated to their highest ex- 

 tremes. For instance ; lead melts at a temperature of 

 594°, but a lead tube fiUed with water, hot or cold, will 

 not melt, though exposed to a red heat (1077°) tempe- 

 rature. To calculate, therefore, that because lead melfa 

 at 594°, and iron (cast) at 2786°, the last must necessarily 

 last longer than the other as a boiler is erroneous. A 

 lead pipe filled with water will last longer than an iron 

 one. I have an instance of this in a boiler for brewing 

 purposes with a copper bottom and lead at the sides. The 

 copper and the lead have been in use for near half a 

 century, but an iron one not so frequently used as the 

 other was corroded through in half the time. It was, 

 however, a wrought-iron boiler. Still, as lead is so 

 peculiarly liable to melt and get out of shajie, copper 

 too dear, brass little less expensive, and -wrought iron 

 soon worn or corroded through, the preference must be 

 given to cast iron. When of good quality, and pains 

 are taken to secure a good cast, this iron is undoubtedly 

 the best and cheapest material that can be employed for 

 making horticultural boilers. 



A cast-iron boiler properly cast is calculated to serve 

 a young man his lifetime, providing he will give a good 

 price for a good article. Cheapness is mostly obtained 

 at the expense of quality, and boilers are no exception 

 to the rule. 



The 4th point may seem ungainly. Why have a boiler 

 larger at the bottom than at the top ? Because when a 

 boUer is thus wider, a larger amount of surface is pre- 

 sented to the immediate action of the fire than there 

 No. 774.— Vol, XXX., Ouj Si;iuri. 



