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diff --git a/1328/CH18/EX18.4/18_4.sce b/1328/CH18/EX18.4/18_4.sce
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+printf("\t example 18.4 \n");
+T1=1100; // F
+T2=70; // F
+t1=T1+460; // R
+t2=T2+460; // R
+k=27; // from appendix
+c=0.14; // from appendix
+row=490; // from appendix
+alpha=0.394;
+theta=4;
+l=10/12; // ft
+x=0.173*10^(-8); // stefan constant
+e=0.7; // emmisivity
+printf("\t values are approximately mentioned in the book \n");
+printf("\t for a \n");
+// Assume the temperature is 500°F after 4 hr. The coefficient from plate to air is the· sum of the radiation and convection coefficients
+hri=(e*x*(t1^4-t2^4))/(T1-T2);
+printf("\t radiation coefficient is : %.1f Btu/(hr)*(ft^2)*(F) \n",hri); // eq 4.32
+hci=(0.3*(T1-T2)^(1/4)); // eq 10.10
+printf("\t convection coefficient is : %.1f Btu/(hr)*(ft^2)*(F) \n",hci);
+hti=hri+hci;
+printf("\t total intial coefficient is : %.1f Btu/(hr)*(ft^2)*(F) \n",hti);
+// For the 4-hr coefficient at 500°F
+hr=2.2; // Btu/(hr)*(ft^2)*(F)
+hc=1.35; // Btu/(hr)*(ft^2)*(F)
+ht=hr+hc;
+printf("\t total intial coefficient is : %.1f Btu/(hr)*(ft^2)*(F) \n",ht);
+h=(hti+ht)/2;
+printf("\t mean coefficient is : %.1f Btu/(hr)*(ft^2)*(F) \n",h);
+X=(4*alpha*theta)/(l^2);
+Y=(h*l)/(2*k);
+printf("\t X is : %.1f \n",X);
+printf("\t Y is : %.3f \n",Y);
+Z=0.42; // Z=f3(X,Y), from fig 18.10
+t=T2+((T1-T2)*Z); // eq 18.53
+printf("\t t is : %.0f F \n",t);
+printf("\t for b \n");
+Z1=0.43; // Z=f4(X,Y), from fig 18.11
+t1=T2+((T1-T2)*Z1); // eq 18.53
+printf("\t temperature of center plane is : %.0f F \n",t1);
+// end