It is well the author of the "leader" in last month's 'Gardener' has laid so lucidly before the readers of this journal the true bearings of "low night" and high day temperature on the setting of Grapes, and Muscats in particular, for I am afraid the advocates of low night-temperature are overlooking the part played by the "higher day-temperature," in effecting for them those splendid "sets" they speak about. I don't wish it to be inferred from this, that I want to run down "cool night-temperatures." On the contrary apart from the actual "setting" of Grapes - I quite agree with all its advocates have said on this subject, for it is in accordance with my own experience and practice for the past thirteen years, which I will now relate.

I entered on my present charge early in September 1868. The first thing that called for particular attention was a Muscat-house, in the middle of a range of three vineries. The Grapes were hanging on the Vines at the time, not quite ripe, and in a very bad condition; the berries shanking, and the wood poor and spindly, and altogether much out of health. I concluded the fault lay in the border. I examined it, and found the soil to be an effete and soapy mass of sour soil. I set about at once to procure some good turfy loam : with this I mixed some burnt earth, charcoal, and some rotten manure, and commenced operations on the border, removing it to within 3 feet of the steins of the Vines. (All the Vines here at that time had been planted in, and confined to, outside borders.) The surface of the remaining 3 feet of border was forked up, and cleared away down to the first roots. After carefully cutting away all decayed and injured roots, and shortening back the strong bare ones, the compost was wheeled in and carefully worked among the roots, which were brought well up to the surface as the work proceeded. As the compost was very dry when brought in, a good soaking of water was given. Both fruit and leaves were hanging on the Vines while these operations were being carried out.

It caused the leaves to flag considerably; but by shading with mats, and syringing the Vines once or twice a-day for some little time, the Vines did not appear to be much checked.

Before the end of October the border was covered a foot deep with dry litter, and over this shutters were put, to throw off the rains, and to keep out frosts. Very little fruit was expected the following season. Forcing did not begin till the first of March, and all went well till the flowering stage. Like a great many more, I had been taught to believe that a high night-temperature, as well as a high day one, was necessary to insure a good "set" of Muscat Grapes. With this in view I gave the order to the stoker to fire harder, and bring the night-temperature up 10° more. (Up to this time it had not been higher on the mildest nights than 50°.) But I soon found out, to my dismay, that the heating apparatus was inadequate to bring the temperature up more than an additional 3° or 4°; and the temperature would run down to a very low point on cold nights, lower than we could at the time account for, and I made sure there would not be a berry " set." I looked anxiously up at the blossoming bunches every day.

Things went on this way for about a fortnight, when I thought I noticed the berries to be increasing in size every day, and one morning, after a rather cold night, dew-drops were found to be hanging on every point of the leaves, to disperse which I had to give the Vines a rather smart tap, at the same time fearing what might be the consequence to the bunches. Imagine my joy when ultimately I found a perfect "set".

Well, I felt I had been taught a lesson, and one not of my own seeking. It had been thrust upon me through circumstances over which I had no control. I was now convinced that a high night-temperature was not necessary for the wellbeing of the Vine. But with regard to the " setting" of the fruit, I still had some doubt about the "low night-temperature " being the direct cause of so good a set of berries.

I felt I had yet more to learn on this point. The vinery was an iron one, and this to a great extent accounted for its being so difficult to heat by night, and for the fact that it run up quickly by day with sun to a high temperature. As I could gain no further definable knowledge, for that season at least, on the setting point, I contented myself with trying to secure as good results the following year as was possible under the circumstances. As I had anticipated, the Grapes were nothing to boast of; still, they were very fair, and finished off well, with not many shanked berries. The following season (1870) I commenced to force the first week in February. Instead of the dry litter on the border, I put 3 feet of hot dung and leaves, and kept this renewed till the ripening stage of the Grapes was reached. I also made daily notes of the day and night temperatures, also of the weather, from the beginning of the forcing to the finishing off of the Grapes, in the hope that I might gain some additional knowledge on the "setting" question. The season passed over, however, without my gaining anything very definite on this point. Like the previous season, it had been a very beautiful and sunny one, especially all through the blooming period.

I had a splendid "set," and the Grapes were fine both in bunch and berry, and finished off with a good colour. Some of the bunches were 5 lb. in weight, and the average through the house 3 lb. The Vines were in robust health, and showed they were benefiting by the new compost. I had had no misgivings this time on the score of the "low night-temperature." One thing I had observed particularly, as I had observed the previous season, that two Vines at the hottest end of the house, and immediately over two 6-inch flow-pipes direct from the boiler - one for the heating of this house, and the other, which had to pass through it on its way to heat the early vinery - had by far the best set bunches.

I commenced forcing again for the season 1871 at the same time and under the same circumstances as the last. But what a contrast in the weather to the two previous seasons. It turned out to be a cold, wet, sunless, and late spring. There was barely one sunny day all through the blooming period. And what about the "set"? Well, it proved to be as remarkable, in contrast to the two previous ones, as the weather was. In place of a "good set," there was a most wretched one - not a full or presentable bunch in the whole house, except on the two Vines over the hot-water pipes, and these were not nearly so full as previously. There were nine Vines in the house - seven Muscat of Alexandria, and two Black West's St Peter. The latter, at the cool end of the house, had not a dozen set berries on them.

On comparing my notes which I had of the temperatures for the two last seasons, I found the night-temperature had differed but little. On very mild nights it had not been higher than 50°, and on the coldest as low as 42° to 45°. There was, however, a very great difference in the day-temperatures during the blooming periods. For the season 1870, with bright sun, the temperature had run up to 80° and 85°, with air on. But for the dull period of 1871, with but little or no sun, we could not force the temperature higher than 55° to 60° at the most, with fire-heat. From this I concluded that I had gained the information I had so much desired, and led me to conclude that " low night-temperatures " have very little to do with the "actual setting" of the fruit; and that a rather high day-temperature, with "sun-light," and a moving atmosphere, are the prime necessary agents for a good " set," especially for Muscat Grapes.

It is said that during the dark hours of the night "all nature" is at rest. I cannot say if my premisses be correct, but I think the pollen and sexual organs of flowers are not in a state to be fructified during the dark, cool, and moister atmosphere of the night, and that it requires the influence of sun-light, a warmer and drier air, to bring them to this state. J. K. K.

Herts.