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Direct Evaporative Cooling
Indirect Evaporative Cooling
Skill Development Exercises for Chapter 9
Append i x A: Thermodynamic Properties of Moist Air
Append i x B: Dimensions , Units, and Unit Conversion Factors.
Append ix C: Climatic De sign Information
Append ix D : Thermodynamic Properties of Water at Saturation.
Skill Development Exercises.
Preface
Psyc hrometrie s is a tool HV AC designers use to det e rmin e the amount of moi st ur e in the air and to provid e so l ution s to d es ign e rs for th e ultimate comfort of bui lding occupants. It ca n be use d to size air handling un its; optim ize energy performan ce; id e ntify contro l se nso rs for building automat ion; de sc ribe the performanc e of cooling coi ls, coo l ing tower s, and humidification eq uipm e nt; and eva l uat e he at recovery stra te g ie s.
Ye t the use of p syc hrometrie s and th e psyc hrom et ric c hart is diffe rent from de sig ner to de s igner. Some do not u se the psyc hrometric chart , relying instead on simp lified formulas or comp lex computer si mulation s. Oth e rs use the chart onl y for s pecia l si tuation s, suc h as indoor sw immin g poo l applications. And some use it as their primary sys te m evaluat i on tooL
This cou rse is meant to cover all of th ese uses of th e p syc hrom e tr ic chart, to ha ve so mething for all these different ba c kground s, and to be an introdu c tion for the yo ung designer w ho ha s yet to pi c k an approach. The COUT::;e addresse s the use of p syc hrom e. trics and the psychrometr i c chart fOT typical app li cations and sys tem s and include s so me th eory. Thi s theory not on ly se ts the b asics but also gives stud e nt s an appreciation of th e si mp l ification th at the p syc hrom etric c hart provides. The psychrometric chart g i ves a v isua l description o f HVA C d es i g n , one that could ne ve r be appreciated from fonnu l as a lo ne .
This secon d e d it ion of the p syc hro metri cs se lf-directed l earn ing (SOL) course w a s rewritten in an attempt to teach the fundam e ntal s of psyc hrom e t ri cs in about half th e tim e as the prev iou s vers ion . Th e author ha s use d h is 4 1 yea rs of experience in the H V AC industry as the expertise for th e format and content.
Acknowledgments
I need to acknowledge a few folks who he l ped me out on this first publishing adventure of m y life. My wife Jo An n was the person who put my sc ribble in to a nice Word document. John Duren , Sa les Enginee r for MPSW in Phoenix , did var iou s eq uipm ent se l ections that a re used in the course. Mick Schwed ler and John Murphy from Trane App li cat ions Engineering Department in L a C rosse, W i sco n s in , we re there w h e n I need so me technical help an d rev iew. And I wou ld lik e to thank ASHRAE staff for their understanding an d h e l p to make this a finished publication.
Introduction to Psychrometries
Stu dy Ob ject iv es
After co mpl e ting thi s c hapt e r , yo u should be able to o understand t he ba sic proce sses of p syc h rome trie s, o understand enthalpy and vo lumetric airflow , and o understand the ba s ic formula s of HV AC d es ign.
Instru ction s
Rea d th e mat e ria l in C hapter I At the end of th e c hap te r, complete th e ski ll d ev elopm e nt exe rc ises without referring to th e tex t.
Introduction
Psyc hrom e trie s is an analysis tool that HV AC eng in ee rs use to pr ov id e so lution s to co mfort iss ues. Th ese iss ues can be re lated to hum a n comfort or pro cess comfort dep e nding on the applications.
If th e air s urroundin g u s we re totall y dry, our job as HV AC engineers wou ld be vel)' easy and probab ly boring. But, b ec au se all air we work with co ntain s so me amount of moi s ture in the form of wa te r va por , our job s ge t mor e comp lex.
Th e four ba s ic proce sses that an H V AC sys te m can pe rform on mo is t air are as follows:
Coo ling- Lowering the air temperatu re
Heating- Rai s ing the air temp era tu re
Humidification- Rai s ing th e moi sture content in the air
De humidification - Lower ing th e moisture cont e nt in th e air
No te that HV AC processes can also be a combination of th e above four bas ic actions. Th ese combinations include the fo ll o w ing :
Heatin g and humidification - Increasing th e temp era tur e and moisture co nte nt of th e air at th e same time
Heati ng and dehumidification- I ncreasing the temperature and d ecreas in g the moisture content of the air at the sa m e time
Coo lin g and humidification - Dec reasing th e te mp era tur e and in creas ing the moi st ure content of the a ir at the sa me time
Coo lin g and dehumid ifi cat ion - Decrea si ng th e temperature and moi st ure co nt e nt of the ai r at the sa me time
These combination processes pro v ide an infinite number of potentia l act i ons. Fo r exa mple , cons id er the cool ing and dehumidification combination proc ess. We ha ve a so lution that drops the tem perature 25 degrees and only drop s th e dew point (defined later) 1 degree. Another so lution drops the tempe rature 10 degrees and the dew point 10 degree s. So, there are thou sa nd s of so lut ions with too man y temperature and dew-poin t combinations to li st.
Enthalpy
We will use the property of the enthalpy of a i r throughout this cou rse. Enthalpy is th e s um of the in terna l energy or the total heat co nt e nt of the ai r In other wo rd s, warm and humid air can have the same heat conten t as hot and dry a i r. So th e e nergy required to coo l wannlhumid air in the Gulf Reg ion of No rth Ame ri ca might be clo se to the energy required to coo l ho t/dry air in the Southwest d ese rt s. Ent halp y h is s ubdi v ided into th e follow in g:
hda enthalpy of dry air at 0% relative hum idi ty h s enthalpy of sa turated air or 100% relative humidi ty h as enthalpy d ifferences between hda and h s
Air Density
E leva tion ha s an effect on psyc hr ome tric ana lyses. As e l eva tion c hang es, so doe s the ai r density. This mean s the constants used in equat ion s will change and differ e nt psychrometric charts (Chapter 3) are required for proper calculation.
For thi s co ur se we w ill use sea leve l as atmospheric pressure for all calculation s unle ss othe rw ise noted.
Volumetric Airflow versus Mass Flow Calculations
For easier understanding, we wi ll use vol umetric airflow in cubic feet per minut e (cfm) rather than ma ss flo w for our calcu lat i ons throughout this course. Standard air i s defined as air at sea level or 29.92 in. Hg of barometric pressure and 69.5 ° F 'db ' The density of air at sea le ve l is 0.075 Ib/ft ) .
The thr ee e quation s we w ill u se in our calcu l ations are for se n sib l e heat (q , ), th e total hea t required (q,), and l atent heat (q ,): qs = 1.085 >< cfm >< (I) - (2) temperature (1·1 )
where the con s tant 1.0 85 is deri ve d from the follo w ing:
0.075 Iblft 3 x 0.24 Bt ul lb ·oF x 60 mi nl h 1.0 8
where 0.24 Bt ul lb ·oF is th e specific heat of air.
q, = 4.5 x cfm x (h. - "2) enthalpy (1-2)
w here the constant 4.5 is deri ve d from the following:
0.075 Ib!ft3 x 60 minlh 4.5
qf=4840 x cfm x (W 1 - W 2 ) humidity ratio (1-3)
where the constant 4840 is de rived from the following:
0.075 Ib / ft 3 x 10 75 Btul lb x 60 minlh 4837.5 4 840
where 107 5 BtuJ1b is th e e nthalp y (h ) of air at 32 ° F for th e eva poration of water to vapo r.
Skill Development Exercises for Chapter I
Complete these questions by writing your answers on the worksheets at the back a/this book.
I-I How many basic processes of air conditioning can b e perfor m ed on moist air?
a) Two
b) Three
c) Four
1-2 Wh ic h co mbination p rocess w ill in crease both the te mp erat ure and th e moi sture content?
a) Coo ling and dehumidification
b) Heating and dehumidification
c) Heatin g and humidific a tion
1-3 Enth alpy is th e t o ta l heat co nt en t of the air.
a) True
b) Fa lse
1-4 C h ange in e leva tion ha s no effect on the air density_
a) True
b) Fa l se
Properties of Moist Air
Study Objectives
Afte r comple tin g thi s chapte r, you s h ould be able to o define s ome fundam e ntal propertie s use d in p syc hrom e trie s and o und e rstand how to u se Appendix A.
Instructions
R ea d th e mat e rial in C hapter 2. At the end of th e chapter, complete th e skill d ev elopm e nt exe rci ses without re ferring to th e tex t.
Introduction
This chapter d e fine s the propertie s that a n HV AC engineer us es to do psychrometric analy s is The propertie s are temp era ture , humidity , e nthalpy, and specific vo lum e.
Temperature in g:
Th e temperature s we are concerned about in HV AC sys te m s are the foll ow -
Dry-bulb temperature: The me asure of th e surro unding air te mp e rature wit h a sta ndard thennomet er in degrees Fahre nh e it ( OF) without infl uence on the th e nnom e ter b y he a t so urce s or so lar heat gain.
Wet-bulb temperature; Th e mea sure of th e moi st effec t on th e evapo ration proce ss in th e air. Us ing a s tandard dry-bu lb therm o meter , place a cotton soc k on th e se ns ing portion Next, soak the soc k in amb ie ntte mp e r atu r e w ater and, b y rotation , mo ve surround in g a i r across the sock. Th e temperatur e w ill drop belo w ambient b eca use o f th e evapo rat i ve o r cooling e ffec t on the se n s ing bulb. It w ill continue to drop until mo s t of the wa te r i s eva porated int o the surrounding ai r. Thi s is th e we t-bu lb temperatur e and may also be called we t-bu lb dep r essio n. Any further dr yi n g of the soc k w ill result in t he temperature goi ng back up to th e ambient dry-bulb te mp e ratu re.
Dew- po i nt temperature: Th e m eas ure of th e dry - b ul b te mp e r a tur e at th e poi nt w h ere wa te r va p o r star ts to condense to liq uid o r be r e m oved fro m th e air . Thi s is al so re fer red to as th e condensation point, beca use it is th e te mp e ra tur e a t w h ic h th e wa te r turn s to l iquid fro m va po r in th e a ir s tr e am. Sat u ra ti on tempera tur e : Th e temp e ra tur e at w h i c h th e a ir ca nn o t h o ld a n y a dd it iona l wa te r va po r. A t th e sa tu rat ion te mp era t ure, th e d ry - b ul b, we t-bu l b , a nd dew -p o int te mp e ra tu res a re id e nti c al.
Humidity
Enthalpy
H umid i ty is th e moi s ture in the a i r. We ca n ta l k a bout it in two ways:
H u mid it y r a ti o: T he ac tu a l weig ht in po und s of wa ter va p or per po und o f d ry ai r (lb )j lb da ). No te th a t in so me HV AC p syc hro m etr i c ca lc ul a ti o n s y o u m ay see grai n s o f m o istur e p e r pou nd of d ry a i r (g r/ lbda ), wi th 7000 g rain s e qu a l to I lb Ei th e r c alcul a ti o n w ill res ult in th e sa m e a nswe r
Re lat ive hu m idi ty: T he ac tu a l a m o unt o f moi sture in t he a i r at a g i ve n d ryb ul b te mp era tur e ve rs us th e m ax imum a mou nt o f m o is tur e in th e air at th e sa m e d ry - b u lb te mp e rat ure. It is ex presse d in perce n tage beca u se i t is a pa rtial m o is tu re l m ax imum m o istu re ra ti o. A t con sta nt mo isture co nt e nt , as so on as th e dry - bulb te mp e ratur e c ha nges, so do es th e re l a ti ve humid ity .
Th e e ne rgy co nt e nt o f a ir is d e fin ed as th e e nt hal py of th e a i r o r th e to ta l hea t co nt e nt of th e ai r. It is ex presse d in Brit is h th e n n a l uni ts (B tu) p er p ou nd o f d ry air (B t ul lb da ). Aga in , wa rm lh umid a ir ca n have th e sa m e e nth a l py as ho t/dry a ir, s o it ta k es th e sa me a m o unt o f ene rgy t o co o l e ith e r a irstre am to a co mfo rt ab le co nditi o n .
Specific Volume
Spec ifi c vol um e is th e cu b ic fee t p er p o und o f d ry air (ft 3/1 bda ) It is th e in ve rse o f air de ns it y ( lb/ ft 3).
No te th a t s p ec i fi c vo lum e c ha nges as th e dry -b u l b te m pe ra tur e c han ges, but not nea rl y as mu c h as it c ha nges w ith th e effec t o f hi g he r a ltitud e.
Using Appendix A
Th e tab le in A pp e ndi x A li sts th e rmod y na mic prop e rti es of moi s t ai r a t 14. 696 p s ia . Fo r e a c h dry-bulb te mp e rat u re in of, we have va l ues fo r th e fo ll owi n g:
Humidi ty rat io at sa turati on
Specific vo lum e a t dr y, sa turat ed, an d d i fferentia l co nd it io ns
Sp ec ifi c e ntha l py a t d ry, sa turat e d , a nd di ffe re nt ia l co nditi o ns
Specific e ntrop y at dry, sa turated , and differentia l conditions (not used in this text)
We will use this table as we go through the text.
Terminology and Symbols for Psychrometries
h e nthalpy of moi st ai r, Btu / lb
ha spec ifi c e nthalpy of dry air , Btullb
h w spec ifi c e nthalpy of water vapor, Btullb
p total pressure , us uall y barometric , in. Hg
Pw partial pr ess ure of water vapor, in. Hg
P a partial pr ess ure of dry air , in. Hg
q rate at w hich heat is transferred to a proce ss, Btulh
tdb dry-bu lb temperature of moist air, of
t \Vb wet-bu lb te mperature of mo ist air , of
t dp dew -p oint temperature of moi st air, of
v spec ific vol ume of moi s t air , ft. 3/ 1b
va spec ific vol ume of dry air, ft 3/ 1b
Vw spec ifi c vo lume of water va por, n3/ 1b
vs' Vg spec ifi c vo lume of saturated water vapor, ft 3/ 1b
W humidit y rat io of moi st a i r, Ib (water)l lb (dry air)
Ws humidity ratio of moi s t air at satura ti on,lb (water)l1 b (dry air)
$ re lati ve humidit y the ratio of actual moi s ture amou nt to maximum moi st ure amount , % rh
For d im e ns io ns and unit s used in air -conditioning applications and a table o f unit conve rs ion fa ctors for converting b etween In ch -P ound (l-P) and SysInternational (SI) mea s urement unit s, see Appendix B.
Skill Development Exercises for Chapter 2
Comp l e te these questions by writing your answers on the worksheets at the back a/this book.
2-1 Dr y -bu lb temperature is mea s ured w ith a we t soc k arou nd th e se n s ing bu lb .
a) True
b) Fa l se
2-2 Saturati on t e mp e ratur e of ai r is the point at which the dry-bulb , we t-bu lb , and d ew- point t e mp e rature s are equa l.
a) True
b) Fa l se
2·3 R e lat ive hum idity doe s not change a s the dry-bulb t e mp era tur e changes.
a) True
b) Fa l se
2-4 The dry-bu lb t empe ratur e can be above th e d ew - point te mp e rature
a) True
b) Fa l se
2-5 According to Append ix A , what i s th e s pec ific entha l p y hs of sat urated air at 40 ' F?
a) 15. 23
b) 9.6
c) 5.8
d) No ne of t he abo ve
2-6 According to Appe ndix A, unde r the sa m e condition c it e d in Exercise 2 - 5, what i s th e s pec ific vo lum e v?
a) 12.69
b) 12.59
c) 0.105
d) No ne of t h e above
2·7 Acco rdin g to Ap pendix A , w hat is the s p ec ifi c en th a lp y of dr y air 17 (1 a t 100 ° F?
a) 29.27
b) 47. 73
c) 24.03
d) No ne of t h e abo ve
2-8 Accor din g to Appe ndi x A , und e r th e sa me conditio n cited in Exercise 2 - 7, w ha t is the s pecific volum e v?
a) 19.15
b) 19 .80
c) 15.45
d) No n e of the a bo ve
Introducing the Psychrometric Chart
Study Objectives
After completing this chapter, you s hould be able to
o describe how the psychrometric chart was developed, o understand how to read the p syc hrometric chart, and o use climatic de s ign information from table s pub li she d by ASHRAE.
Instructions
Read the material in Chapter 3. At the end of the chapter, comp le te the s kill de ve lopment exer ci ses without referring to the text.
The Modern Age of Psychrometries
In this chapter, you wi ll learn about the psychro metric c hart and ho w to use it in HV AC problems. You wi ll see how to co nstruct and then use the psychrom et ric chart.
The p syc hrometric chart was developed by Wi lli s Car ri er in the early 1900 s. It ha s been refined over time for more acc ura cy to pro vid e better re su lt s. The chart conta i ns seve n important p syc hrom e tric varia ble s, represented on the chart by the following sy mbol s:
'db dry-bu lb temperature
'wb wet-bu lb te mp e ratur e
tdp dew-point temperature
$ re lative humidit y
h e nthalpy
W humidit y ratio
v spec ific vo lume
Creating the Psychrometrie Chart
We wi ll no w discuss ho w to construc t the psychrometric c hart and plot the seve n important properties on the chart. Using Figure 3 -1 , start with the x-axis (the hori zo ntal line across the bottom) and plot dry-bu lb temperatures on a linear sca le from low on the right to high on the left.
Next we go to Ap pendix A and get th e saturated humidity ratio Ws va lue s from 32 ° F to 120 ° F. Then , put the y -a xis (the vertical l in e on the ri g ht s id e) on a lin ear sca le from Iowan the bottom to high o n the top.
We deve lop the sat uration lin e (the h eavy dark curve s h ow n in Figure 3 -1) by the int e r sect ion of the Ws va lue and the vertica l dry-bu l b lin e. Remember, the dry-bulb, wet - bu lb, and dew-point te mperatur es are eq ual on the satu rat ion lin e. Lines of constant h u mi dity ratio are all hor izonta l.
Figure 3-2 sho ws that the dew-point temp erature is w here the dry-bulb tempe rature intersects the saturatio n l ine. A lin e of constant dew point goes horizo nta ll y on the p syc hrom e t ri c chart.
Go ing to Figure 3- 3, we can ge t the value of the ent halp y at sa turation (h s ) and again p l ot that va lue on the saturation lin e for that dry-bu l b temperature.
To find the other end of the entha l py lin e , we simply take the hs va lue and go to Appe ndix A a nd look fo r a very close value i n the hda column. Once we find i t, t h at dry - bu lb temperature is th e int ersectio n po i nt for that e nt h a l py li ne w ith the x -axi s.
For example, 60° F db ha s a va lu e of26.4 Btu/l b , so we plot thi s va lu e at the 60 ° F sa tura t io n te m pe ratu re. We go to Ap pendix A a nd searc h for a va lue of 26.4 Btullb in th e hda co lum n and find it at 100 ° F db . Those two points es tabli sh t h e 26.4 Btullbda e nt h a lpy l ine. Lin es of constant e nthalp y are s l oped and are so li d da rk .
Fig ure 3 - 1 Begi nnin g th e psychrom e tric chart .
3-2
Plotting int erse ction of
Figure 3-3
Plotting enthalpy on the psychrometric chart.
Figure
Figure 3-3 also s ho ws that li nes of constant wet-bulb temperature are almost parallcl to lin es of constan t enthalpy. Lin es of cons tant wet-bulb tempe ratur e are s lop ed and dotted, as shown in Figure 3-4.
Figure 3-4 s ho ws speci fic vo lume li nes. We p lot them by go i ng to Append i x A and, at a given sat uration temperature, getting the V s va lu e and in sert ing it on the satu ration line . Then we look at the tabl e for the sa m e va lue at a hi g he r temperatur e, and that is th e x-axis intersec tion point for th e o th er end of the specific vo l ume lin e.
Finding Seven Psychrometric Quantities
The psych rometr ic cha rt shown in Figure 3-4 is s uffi cient to provide imm ediat e and comp l ete characteristics of a moist air parcel, even if only a small amount ofinfonnation is known about that parcel. More spec ifi ca ll y, ifan y two of the seve n important p sych rometric variables (tdb, 'dp' 'wb, q" h, v, It) of a moi st air sam pl e are given (for a specific b arometr ic pressure), then a ll of the remaining ones ca n be determ ined immediate ly fro m the chart.
Example 3-1
Problem Given a samp l e of air whe re {db = 70 ° F and = 60% rh, determ in e its dew point.
Solution Using Figure 3-4, the location point is at the int ersect ion of the co ndition s stat ed in the probl e m . Moving to the left in a strai gh t li ne indicates that th e sa turation curve is crossed at a temperature of 55 ° F. This is the dew-point tempe rature.
Example 3-2
Problem What is the e nthalp y of th e 70° F and 60% rh parcel of air fr om Examp l e 3-1?
Solution Again using F igure 3-4 , the lo cat ion point is the sa m e. Follow i ng the lin e of constant enthalpy up the enthalpy sca le revea ls that the ent halp y of this point is 27.0 BtuJlb dG'
Example 3-3
Problem Find the wet-bulb temperature for the point in Example 3- 1
Solution Aga in us in g Fig ure 3-4, fo ll ow the constant wet-b ulb lin e to th e saturat ion lin e, then drop stra ight down to re ad a temperature of6 1OF, t he we t- bu lb temp e rature.
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overtaking him, we make comfortably sure that religion lends itself as deftly as journalism to the light-hearted drolleries of the cruel.
Novelists, who understand how easy a thing it is to gratify our humorous susceptibilities, venture upon doubtful jests. Mr. Tarkington knows very well that the spectacle of a boy dismembering an insect calls for reprobation; but that if the boy’s experiments can be described as “infringing upon the domain of Dr. Carrell,” they make a bid for laughter. “Penrod’s efforts—with the aid of a pin—to effect a transference of living organism were unsuccessful; but he convinced himself forever that a spider cannot walk with a beetle’s legs.” It is funny to those who relish the fun. If it does not, as Mr. Pater advises, make suffering ridiculous, it makes sympathy ridiculous, as being a thing more serious than the occasion warrants. The reader who is not amused tries to forget the incident, and hurries cheerfully on.
A more finished example of callous gaiety, and one which has been more widely appreciated, may be found in a story called “Crocker’s Hole,” by Blackmore. It tells how a young man named Pike, whom “Providence” had created for angling (the author is comfortably sure on this point), caught an old and wary trout by the help of a new and seductive bait. The over-wrought, over-coloured beauty of Blackmore’s style is in accord with his highly sophisticated sense of humour:
“The lover of the rose knows well a gay, voluptuous beetle, whose pleasure it is to lie embedded in a fount of beauty. Deep among the incurving petals of the blushing fragrance he loses himself in his joys till a breezy waft reveals him. And when the sunlight breaks upon his luscious dissipation, few would have the heart to oust such a gem from such a setting. All his back is emerald sparkles; all his front, red Indian gold, and here and there he grows white spots to save the eye from aching. Pike slipped in his finger, fetched him out, and gave him a little change of joys by putting a Limerick hook through his thorax, and bringing it out between his elytra. Cetonia aurata liked it not, but pawed the air very naturally, fluttered his wings, and trod prettily upon the water under a lively vibration. He looked quite as
happy, and considerably more active than when he had been cradled in the anthers of a rose.”
The story is an angling story, and it would be unreasonable to spoil it by sympathizing with the bait. But there is something in the painting of the little beetle’s beauty, and in the amused description of its pain, which would sicken a donkey-beating costermonger, if he were cultivated enough to know what the author was driving at. It takes education and an unswerving reverence for sport to save us from the costermonger’s point of view.
There are times when it is easier to mock than to pity; there are occasions when we may be seduced from blame, even if we are not won all the way to approval. Mrs. Pennell tells us in her very interesting and very candid life of Whistler that the artist gratified a grudge against his Venetian landlady by angling for her goldfish (placed temptingly on a ledge beneath his window-sill); that he caught them, fried them, and dropped them dexterously back into their bowl. It is a highly illustrative anecdote, and we are more amused than we have any business to be. Mr. Whistler’s method of revenge was the method of the Irish tenants who hocked their landlord’s cattle; but the adroitness of his malice, and the whimsical picture it presents, disarms sober criticism. A sympathetic setting for such an episode would have been a comedy played in the streets of Mantua, under the gay rule of Francesco Gonzaga, and before the eyes of that fair Isabella d’Este who bore tranquilly the misfortunes of others.
We hear so much about the sanitary qualities of laughter, we have been taught so seriously the gospel of amusement, that any writer, preacher, or lecturer, whose smile is broad enough to be infectious, finds himself a prophet in the market-place. Laughter, we are told, freshens our exhausted spirits and disposes us to good-will,—which is true. It is also true that laughter quiets our uneasy scruples and disposes us to simple savagery. Whatever we laugh at, we condone, and the echo of man’s malicious merriment rings pitilessly through the centuries. Humour which has no scorn, wit which has no sting, jests which have no victim, these are not the pleasantries which have provoked mirth, or fed the comic sense of a conventionalized
rather than a civilized world. “Our being,” says Montaigne, “is cemented with sickly qualities; and whoever should divest man of the seeds of those qualities would destroy the fundamental conditions of life.”
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