451 



FARMERS' REGISTER- ARTESIAN WELLS. 



tected rrom tlie influence of the cooler water above, 

 through which it must be raised at every observa- 

 tion. Otherwise, its temperature will iiill as it is 

 drawn up to tho surface, and it will only indicate 

 in part the heat that prevails below. One of the 

 best means of preventing this effect, would be to 

 enclose the instrument in a thick strong case ot 

 glass, and fill the vacant space around it with dry 

 powdered charcoal or finely carded wool laid loosely 

 in. The case should be so tight as to prevent the 

 entrance of the water. But as a case of this des- 

 cription could not be readily obtained unless by 

 special order at a glass house, a good substitute 

 could be constructed by enclosing a hollow cylinder 

 of baked wood in a water tight covering of sheet 

 iron or lead. The wooden cylinder should have a 

 top and bottom of the same material, the former 

 capable of being screwed off and on. The me- 

 tallic envelope should also have a moveable top, 

 and should be so much larger than the wooden 

 cylinder within, as to allow a packing of powdered 

 charcoal belween them. The thermometer, con- 

 tained in the inner vessel, should be surrounded 

 with a packing of the same material. Thus sur- 

 rounded with a non-conducting envelope, the in- 

 etrument would retain the temperature impressed 

 upon it below, even though raised quite gradually 

 to the surface. Of course, after letting it down to 

 anj^ particular depth, it should be suffered to re- 

 main in that position tor a long time, in order to 

 acquire the precise temperature of the surrounding 

 water. It should theu be drawn vip as rapidly as 

 convenient, and its temperature noted without 

 delay. To avoid the necessity of opening the 

 cylinders at each observation, for the purpose of 

 observing the instrument, a part of the stem or 

 Bcale might be allowed to project through one end, 

 taking care that the perforation in the cylinder 

 through which they pass is perfectly secured by 

 cement against the admission of water. This ar- 

 rangement, however, is by no means necessary, 

 and would be difficult to make secure. 



To those who are provided with a Maxinium 

 Thermometer these precautions would be unneces- 

 ear)', for it is the property of that instrument to in- 

 dicate by its gage or float, the highest temperature 

 to which it has been exposed in observation, al- 

 though the mercury in the stem may subsequently 

 have been much depressed. With an instrument 

 of this description, observations would be more ac- 

 curate, and at the same time much more readily 

 made than by any other arrangement that could 

 be devised, and it would therefore be desirable that 

 those who are about to enter upon experiments of 

 this nature would provide a Maximum Thermom- 

 eter for the purpose. The instrument can be pro- 

 cured in any of the large cities at a moderate cost, 

 probably not exceeding five dollars. 



A close approximation to the temperature might, 

 I think, be obtained by enveloping the bulb in a 

 thick covering of cement formed of melted rosin 

 and bees wax, which, when cold, would form a 

 hard covering, impervious to water, and having 

 but little power to conduct heat. This method, 

 I think, is well worthy of being tried. 



Where there are several wells of different 

 depths near each other, the rate of increase might 

 be ascertained to a certain extent, by placing the 

 thermometer successively at the bottom of each 

 well — but the results would be more satisfactory 

 and complete if progressive experiments were 



made in each. Moreover, such experiments 

 should be repeated several times, and the mean 

 of observations taken. 



9. In whal way or according to what law does 

 the strength of the water in salt weUs vary with 

 the depth ? 



This query which is addressed especially to the 

 proprietors of our western salt works, has been in 

 part suggested by a very curious fact mentioned 

 by Albeiti in a work published a few years ago 

 on the rocks of Wiitembury. This author states 

 that the brine diminishes in strength from the sur- 

 face downwards to a certain depth, where it is 

 almost in the condition oi' pure water, and that 

 beneath this it grows stronger as you descend. 

 The fact is extraordinary and almost incredible — 

 yet it is asserted upon the authority of a great 

 number of carefully executed observations. 



The following table selected from a number of 

 similar ones, will serve as an example of the 

 seemingly inverted arrangement of the water in 

 the upper part of the well, and of the regularly 

 increasing strength beneath. The series of ob- 

 servations were made after the well had remained 

 eight hours without being drawn upon. The unit 

 of measurement referred to in the table is equiva- 

 lent to three and a half English feet. I have not 

 reduced the numbers to feet, because this would 

 have rendered fractional qualities necessary in the 

 columns expressing the depth. 



In another series of observations upon the same 

 well in diflerent circumstances, the maximum 

 strength of the brine, instead of occuring as in 

 the above experiments at 47 or 48 measures below 

 the surface, took place at the depth of 140 mea- 

 sures. The subsequent increase of saline im- 

 pregnation was also a great deal slower, so that to 

 reach brine of 27 per cent., it was necessary to 

 descend to a distance of 197 measures. 



The facts here stated possess the highest prac- 

 tical, as well as philosophical interest; but further 

 experiments are wanting to determine whether in 

 the numerous observations referred to by Alberti, 

 the very singular results which he has recorded 

 were produced by some general cause, or by pe- 

 culiar circumstances of a local character. To 



