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124 REPORT—1849. 
alternately against the right and left sides of the drain, the letter A indicating the 
position of the handle. 
The larger tool, the blade of which is 20 or 22 inches in length, will excavate the 
drain to the depth of about 20 to 22 inches, and the smaller tool, which is usually 
longer, will at one stroke increase that depth to 33 feet, or even more. I have had 
the opportunity of seeing a drain excavated by these tools, which was only 44 inches 
wide at the top, 3 inches at the bottom, and upwards of 5 feet deep. The soil was 
a stiff loam and free from stones, which is necessary to the advantageous use of such 
narrow excavations. 
When a commencement has once been made, the facility of working is remark- 
able ; the tool is pressed down, and the spit of earth detached, with much less exer- 
tion of force than in the case of any other tools. This arises from the spit of earth 
being completely separated from the surrounding soil as the tool descends, so that 
the after-resistance is avoided; and it is only the fore-part of the tool which has an 
obstacle to overcome. On examining tools which have been some time in use, I 
have found the varnish still remaining after the first few inches, showing that the 
upper or after part was but little subjected to friction. 
A little dexterity is requisite in keeping the tool properly along the side of the 
drain, and also in withdrawing the spit of earth when cut out. On the latter ac- 
count the tool must be inclined from the perpendicular, as in the case of other drain- 
ing tools, and not thrust straight down into the ground. On account of the dimi- 
nished resistance, the size and weight of most other draining tools is rendered un- 
necessary, and the handles may be constructed of a lighter and cheaper wood. 
The tool which has been described is the invention of one of the Life-members of 
the Association, who was led to its adoption from a consideration of the advantages 
to be gained by attending to the principle before alluded to, and from a practical 
acquaintance with the subject of draining in a country where the soil is compara- 
tively free from stones. 
On an Oil Test. By JAMES NAsMyTH. 
The author has contrived an instrument by means of which the comparative value 
of various kinds of oil, as lubricating agents, may be ascertained. In all the con- 
trivances which have been proposed as oil tests, a most important element has been 
left out, viz. time, inasmuch as the evil which is experienced from the use of a bad 
quality of oil is only developed after the lapse of several days, when, by the action 
of the oil upon the metal with which it is in contact, together with the action of 
the air, such oils become viscid, and begin to clog instead of facilitating the move- 
ments of the parts of the machinery it was intended to lubricate. 
In the more delicate descriptions of machinery, such as chronometers, watches, 
clocks, &c., such a defect as the thickening of the oil by lapse of time is a most 
serious evil; and in examining into the comparative fitness of certain oils for such 
applications, if we do not include ¢ime as an element in our examination, we shall 
be led to form most false conclusions, inasmuch as it is the case that for the first 
day or two some kinds of oil (linseed oil for example) perform the lubricating duty 
very well, but at the end of the second or third day they become so thick and viscid 
as to entirely arrest the motion of the machinery. 
The most valuable quality in an oil intended for the lubrication of machinery is 
permanent fluidity. That oil which will for the greatest length of time remain fluid 
in contact with the iron or brass is without doubt the most useful for the purpose. 
Hence, as before said, the necessity of including the element of time in any experi- 
ment on the comparative value of such oils. 
Some idea may be formed of the importance of having the means of arriving at 
correct conclusions on this subject, when we know that in some spinning establish- 
ments there are upwards of 50,000 spindles in motion at the rate of 4000 or 50C0 
revolutions per minute! The slightest defect in the quality of the oil in such a case, 
by its becoming viscid, tells in the most serious way upon the quantity of fuel con- 
sumed in generating the power required to maintain at this high velocity such a 
multitude of moving parts. 
The slight increase of fluidity consequent on the rise of temperature, caused by the 
