The proportion of heat utilized depends on the thermal efficiency of the engine, amounting from twelve to fifteen per cent in good condensing engines; in the very best engines of large size it may be as high as twenty per cent.
The last-named are all hot or thermal as well as mineral springs, deriving their heat either from the natural heat of the earth at great depths, or from volcanic action.
I have not said anything of the thermal principles involved in the construction of these engines, as they are precisely the same as those affecting the subject of the present paper.
The thermal efficiency of the best non-condensing engine to that of the gas-engine is in the ratio 4/22.
This process of excluding thermal rays is adopted for the visible rays of the spectrum.
This trouble may be minimised by having the inner surface of the thermal chamber of bright polished metal, since the radiating power of a polished surface is relatively feeble.
Luminous radiation of the more refrangible portion of the spectrum; ultra-violet rays; thermal radiation in the infra-red region.
Response of Mimosa pulvinus to thermalradiation 248 I.
The difficulty may be removed to a certain extent by placing the plant in a thermal chamber, with arrangement for regulating the temperature of the air.
The effect of rise of temperature in acceleration of growth is thus antagonised by the action of thermal radiation.
Thermal stimulus was applied at the middle, when two excitatory waves with their concomitant electric changes were transmitted outwards.
Another difficulty arises from the radiation of heat-rays from the sides of the thermal chamber.
Proceeding further in the infra-red region of thermal rays, it is found that these latter rays become suddenly effective in inducing retardation of growth.
The only way of removing the complication arising from thermal radiation lies in varying the temperature condition of the plant, by direct contact with water at different temperatures.
In connection with this it should be remembered that while the thermal rays induce a retardation of growth, rise of temperature, up to an optimum point, gives rise to the precisely opposite reaction of acceleration of growth.
Beyond this, the infra-red or thermal rays become suddenly effective in inducing excitatory movement and retardation of growth.
This may be due to some slight fluctuation in the temperature of the chamber, or to the effect of thermal radiation from the side of the chamber.
Before inserting the suspected water it is essential that the gelatine be under 40° C, or thereabouts, in order not to approach the thermal death-point of any bacteria.
A fourth point helpful in diagnosis is the temperature which proves to be the thermal death-point.
There is no fixed standard for pasteurisation, except that it must be above the thermal death-point of pathogenic bacteria, and yet below the boiling-point.
The average thermal death-point is at or about 50° C.
This difference in the thermal death-point between bacilli and their spores enables the operator to obtain what are called "pure cultures" of a desired bacillus from its spores which may be present.
Another mode is to raise the pure culture to a temperature approaching its thermal death point.
It is important that the thermal expansion of the two materials which are thus incorporated should be nearly alike, as otherwise warping of the finished sheet is liable to result.
Others again have requisitioned the variability in the amount of the carbon dioxide in the atmosphere--hypotheses which depend upon the efficiency of this gas as a thermal absorbent.
British thermal units, a unit being the heat needed to raise a pound of water to 40° Fahr.
Discussing in detail the performance of such a plant, Mr. Stott concludes that its average total thermal efficiency would be 24.
The angle of torsion when thermal equilibrium is reached, measures the intensity of the incident radiation.
The first station by the Lucca route is San Giuliano, with its thermal springs, temp.
At the entrance into the town is the +Etablissement Thermal Ste.
It has a thermal establishment supplied by an unctuous and clear water, temperature 100° Fahr.
In the neighbourhood are the argentiferous mines of Rocheray and the saline thermal springs of Echaillon.
Consul Sextius Calvinus around the thermal springs, which he himself had discovered.
And this thermal paradise is sketched by Sir Erasmus in language as brilliant and beautiful, as any that ever the other professor Wilson puts into the month of the bard of Ettrick, in his inimitable Noctes Ambrosianae.
Could we, however, have such a splendid thermal temple as that of Riverside attached to our own home, we would certainly never wander away from it to worship at another shrine.
I do not know whether bath-resorts can be described fittingly as sport centres; but it is well to chronicle somewhere the fact that Switzerland is well off for thermal and medicinal baths.
A good many years later he was entrusted by the committee of the British Association on standards of electric resistance with the task of deducing the mechanical equivalent of heat from the thermal effects of electric currents.
From all appearances this basin must have been the scene of thermal activity within a comparatively recent period; but now not a spring can be found with a temperature above that of ordinary spring-water.
Imagine the case of a simple thermal silicious spring, whose waters trickle down a gentle inclosure; the water thus exposed evaporates speedily, and silica is deposited.
Around these immense thermal deposits, the country, for a great distance in all directions, is filled with boiling springs, all exhibiting separate characteristics.
The ketone group corresponds to a thermal effect of 53.
We assume that each carbon atom and each hydrogen atom contributes equally to the thermal effect.
OH may be determined by finding the heat of formation of the alcohol and subtracting the thermal effects of the remaining linkages in the molecule.
By experiment it is found that the thermal effect of a double bond is much less than the effect of two single bonds, while a triple bond has a much smaller effect than three single bonds.
Thomsen deduced that a single bond between a carbon and a nitrogen gramme-atom corresponds to a thermal effect of 2.
The thermal effect of the aldehyde group has the average value 64.
The thermal effects of the halogens are: chlorine = l5.
The thermal effects increase as one passes from primary to tertiary alcohols, the values deduced from propyl and isopropyl alcohols and trimethyl carbinol being:--primary = 45.
The thermal effects of the common organic substituents have also been investigated.
We need only mention here the Iceland geysers, the springs of Plombières, and the well-known thermal springs of Bath and elsewhere in this country.
This structure appears to give polarity to earthquakes--thermal waters and earthquakes--which are all traceable in the direction of the polar grain or cleavage from north to south.
In England, for instance, thermal and saline springs are traceable from Bath, through Cheltenham, to Dudley.
But how comes lime in a state of bicarbonate, dissolved in these thermal waters, to form rocks?
The heat of the earth’s crust was probably then far greater than at present, while a high temperature prevailed at comparatively small depths, and thermal waters abounded.
A hard stratum of travertine a foot thick is obtained, from these thermal springs, in the course of four months.
This, and its greater capacity for evaporative cooling (Chevalier, 1985), allows Bassariscus astutus to take advantage of a wider range of thermal environments than these other species.
This suggests that ancestral procyonids may have had poor to modest ability to thermoregulate at high temperatures, a condition that would have limited their ability to leave the thermal stability afforded by tropical forests.
However, at their T{lc}'s, the thermal gradient sustained by these tropical animals is only about 11 deg.
Minimum thermal conductance is readily derived from metabolic chamber data, and it is commonly used to describe an animal's capacity to minimize passive heat transfer.
Comparisons of thermal conductances calculated on the basis of metabolic body size (Mellen, 1963) gave the same results.
I do not know that investigations have been made to determine scientifically their exact thermal influence upon the earth.
It seems saner to seek a cause for the unique daily bath of the Japanese in their also uniquely numerous thermal springs, which occur in no less than 388 different localities.
The gas obtained consisted of a mixture of carbon monoxide, hydrogen, nitrogen and some carbon dioxide and oxygen, having a lower heating value of about 150 British thermal units per cubic foot.
Callendar demonstrated this at a meeting of the Institution of Civil Engineers Committee on thermal standards in 1904.
This equation in effect says that thermal efficiency operating on the Carnot cycle depends upon the temperatures before and after compression.
Indicated thermal efficiency may be defined as the proportion of the total heat of combustion which appears as work done by the explosion and expansion upon the piston.
To set up an absolute standard of thermal efficiency it is necessary to know in a complete manner the physical and chemical properties and occurrences in a gaseous explosion.
It has long been recognized that constant pressure and constant volume engines have the same thermal efficiency for similar range of compression temperature, but Prof.
Theoretical Thermal Efficiency for the Three Symmetrical Cycles of Constant Temperature, Pressure and Volume.
Here also it can be shown that the thermal efficiency depends on the ratio between the temperature before compression and the temperature after compression.
It will be seen that brake thermal efficiency has also increased from 14% to 32%; that is, practically one-third of the whole heat of combustion is obtained by these engines in effective work available for all motive power purposes.
It has been found that two-cycle engines present greater practical difficulties in regard to obtaining high indicated and brake thermal efficiencies, but the thermodynamic considerations are not affected by the practical difficulties.
There is no difficulty in supposing therefore that the carbon in a flame is separated from the hydrocarbon within it by the purely thermal action of the blue burning walls of the flame.
The term "flame" is also applied to solar protuberances, which, according to the common view, consist of gases whose glow is of a purely thermal origin.
The existence of the internal cone and the subsequent thermal effect lead to slight convexity of surface in the outer cone.
The fact is that colourless gases cannot be made to glow by any purely thermal heating at present available, and products of combustion heated to the average temperature of the flames in which they are produced are non-luminous.
The thermal coefficient of expansion of steel and concrete is nearly the same, otherwise changes of temperature would cause shearing stress at the junction of the two materials.
In fact, small differences of composition or variations in thermal treatment during manufacture involve relatively large differences of quality.
It is well known that, at the present period, thermal waters and hot vapours burst out from the earth during earthquakes, and these would not fail to promote the disengagement of volatile matter from the Carboniferous rocks.
It is moreover acknowledged that even those mineral and thermal springs which, in the present state of the globe, are far from volcanoes, are nevertheless observed to burst out along great lines of upheaval and dislocation of rocks.
These thermal waters are most commonly charged with a variety of mineral ingredients, and they retain a remarkable uniformity of temperature from century to century.
