library(MASS)
attach(geyser)
par(mfrow=c(2,3))
truehist(duration, h=0.5, x0=0.0, xlim=c(0,6), ymax=0.7)
truehist(duration, h=0.5, x0=0.1, xlim=c(0,6), ymax=0.7)
truehist(duration, h=0.5, x0=0.2, xlim=c(0,6), ymax=0.7)
truehist(duration, h=0.5, x0=0.3, xlim=c(0,6), ymax=0.7)
truehist(duration, h=0.5, x0=0.4, xlim=c(0,6), ymax=0.7)

breaks <- seq(0, 5.9, 0.1)
counts <- numeric(length(breaks))

for (i in 0:4) {
  counts[i+(1:55)] <- counts[i+(1:55)] +
  rep( hist(duration,breaks=0.1*i + seq(0,5.5,0.5), plot=F)$density, rep(5,11))
}
plot(breaks+0.05, counts/5, type="l", xlab="duration", ylab="averaged", bty="n", xlim=c(0,6), ylim=c(0,0.7))