In the December number of the ' Gardener' I made a few remarks on this subject. They were principally put forward in the form of queries, and in a way (I thought) so as not to hurt the prejudices of any one, knowing that a wide difference of opinion existed on the matter. The subject was, however, interesting and important at a time when the price of coal had reached a figure which is already seriously impeding the progress of horticulture. It appears, however, that there are always some people who, like the Irishman, are spreading out their coat-tails to be trodden upon, and amongst this class is clearly to be reckoned your Broughty-Ferry correspondent, "D. J." His remarks, which he calls an array of facts (!!), are likely to have but scant consideration, placed as they are in uncomfortable juxtaposition to your own excellent leader on the same subject; and his situation is not at all likely to be improved by a critical analysis of his well-considered paper. In the course of business I am in the habit of passing frequently a certain street orator, a "high-pressure reformer on general principles," as Artemus Ward would say - whose great forte consists in knocking down his imaginary opponents in argument; but then, he sets them up himself, and having placed them in the most assailable position, he proceeds to demolish them in the most signal manner.

Now "D. J." reminds me forcibly of my spouting acquaintance of the street corner. To accept the plain reading, or even the words of the text, in my December paper, did not suit his purpose exactly, and so he proceeds to alter both to his satisfaction, and having accomplished this, he sets himself up to "put down ,: "J. S." and "such-like" (how very courteous!) and he is quite ready to give us facts for "a lifetime," if he thinks it "worth his while." Surely the Editor will never permit such an oracle, and one so modest withal, to be lost to the readers of the ' Gardener,' but will exert those persuasive powers which editors know so well how to use, to induce this colossus of the "north," who wields his pen as he would a spade, to come forth and lend us his aid.

Now for " D. J.'s " handy way of " putting it." He says, "According to the opinion of 'J. S.' we may haul out our boilers and pipes." I expressed no such opinion, nor even insinuated anything so absurd. Again he says, "I fear ' J. S.' is going to let his craft adrift altogether. A difference of 55° in six hours! "My words were, "If the temperature of a vinery must be kept low enough at night to arrest perspiration, it means that Muscats that have been allowed a temperature of 90° or 100° during a sunny day, when they are perhaps in bloom, must be treated to a temperature of 50° at night, to fall maybe to 45° before sunrise," thus allowing eighteen or twenty hours for the subsidence of the thermometer, taking its maximum at noon. Then, again, "D. J." makes me to say that I have "proved that Muscats will set like Peas in a temperature of GOV My words were, "Will set as thick as Ham-burgs in a temperature of 60°," etc. I think we may be permitted to doubt both the "facts " and intentions of one who deals in such an unscrupulous manner with his opponent's text. But let us hope that as "D. J.'s " literary experience improves, his knowledge and discretion will improve also.

His paper shows abundantly that there is a want of information on the subject of temperatures in regard to plant life. In my last I referred chiefly to experience, and will do so again; but for the sake of those of your readers who have not such books at hand, and who would like further evidence on the matter, allow me to give the following extracts from Dr Lindley's ' Theory and Practice of Horticulture' on the subject of low night temperatures for the Vine: -

"In no part of the world are the Grapes more delicious than in Candahar and Cabul. On the 30th of June, this traveller (Mr Atkinson) saw donkeys laden with panniers of fine purple Grapes; and at the same time the paper on which he was writing curled up and became as crisp as if it was before a blazing fire. When he reached Cabul, in August, he found the bazaar filled with delicious Grapes in astonishing profusion. But what sort of nights had the troops in the spring of the year, when the Vines were growing and flowering and preparing themselves to bear fruit? On the 7th of March, near Shikapore, 200 miles south of Candahar, and above 500 south of Cabul, in the desert, we are told that the march took place on 'a brilliant starlight night; frost seemed to be in the air, it was so cool and bracing; after midnight the servants made up a blazing fire, for the north wind was blowing bitterly cold, and the traveller was glad of hot brandy-and-water.' Nevertheless, the day before, Mr Atkinson had been grilling at Shikapore; and the march was over level plains, and not among the mountains.

Two days afterwards the weather is described as being oppressively hot at mid-day; then on the 19th March there was a hail-storm at night, and the air was ' cold and bracing,' and so on.

"Here, then, in a country totally different from the islands of the Mediterranean, where the Grapes are famous for their excellence, we have violent variations in temperature between day and night in the month of March, when the Vines are shooting; the air is cold and bracing by night, and the sun is grilling by day".

Then again, in the same page, Dr Lindley gives the extreme fall of temperature during the night in the interior of tropical Australia, as recorded by Sir Thomas Mitchell, and which was made the subject of comment in the ' Journal of the Horticultural Society of London' at the time; but space forbids me quoting at length here: your readers must refer to the book itself. Only I may quote that the Cymbidium canaliculatum, the only orchidaceous epiphyte observed, was in flower under a night temperature of 33° and 34°, that by day not exceeding 86°. Here is a range of 53°, where plants more susceptible of changes of temperature than the Vine are found growing. And, further, judging from Mr Atkinson's experiences about Shikapore - grilling by day and frosty by night - we can only conclude that the daily range of the temperature must have considerably exceeded 55°. I am also informed from private sources, though I cannot give statistics, that the difference between the day and night temperature in some of the Vine-growing districts in the north of France is something remarkable.