The clock below sets itself upon you looking at a clock in mume on the hour. 
There's no way round this with the JMC tick commands although you can manually 
set the time with sethr <hour>. The beep can be removed but the time to dusk/dawn 
then becomes unreliable (the delay is needed to ensure variables are updated)

The below lines should all start with a #, if not they've been wrapped round.

#multiaction on
#ticksize 60
#tickon
#sub {#10 SECONDS TO TICK} {}
#alias {sethr} {#variable hr %1|#math hour {%1+1}|#tickset}
#action {#TICK} {#math {hr} {$hr+1}|#math {hour} {$hour+1}|#if {$hour==24} {#variable hour 0}||#if {$hr==24} {#variable hr 0}|#var d 1|#var {tod} DAY|#bell|#if {$hour<$dawn} {#var {tod} NIGHT|#math ttd {$dawn-$hour}|#showme $ttd mins till sunrise|#var d 0}|#if {$hour>=$night} {#var {tod} NIGHT|#math ttd {$dawn+24-$hour}|#showme $ttd mins till sunrise|#var d 0}|#if {$d!=0} {#math ttn {$night-$hour}|#showme $ttn mins till sunset}|#showme TIME - $hour:00} 
#action {The current time is %1:00 am.} {#math {hr} {%1}|#tickset}
#action {The current time is %1:00 pm.}={#math {hr} {%1+12}|#tickset}
#action {%1, the %2 of Foreyule, Year %3 of the Third Age.}={#var dawn 7|#var night 19}
#action {%1, the %2 of Astron, Year %3 of the Third Age.}={#var dawn 7|#var night 19} 
#action {%1, the %2 of Forelithe, Year %3 of the Third Age.}={#var dawn 6|#var night 20}
#action {%1, the %2 of Afterlithe, Year %3 of the Third Age.}={#var dawn 5|#var night 21}
#action {%1, the %2 of Wedmath, Year %3 of the Third Age.}={#var dawn 4|#var night 22}
#action {%1, the %2 of Thrimidge, Year %3 of the Third Age.}={#var dawn 7|#var night 20}
#action {%1, the %2 of Rethe, Year %3 of the Third Age.}={#var dawn 8|#var night 18} 
#action {%1, the %2 of Solmath, Year %3 of the Third Age.}={#var dawn 5|#var night 21}
#action {%1, the %2 of Afteryule, Year %3 of the Third Age.}={#var dawn 8|#var night 18}
#action {%1, the %2 of Winterfilth, Year %3 of the Third Age.}={#var dawn 6|#var night 20}
#action {%1, the %2 of Blotmath, Year %3 of the Third Age.}={#var dawn 7|#var night 22} 
#action {%1, the %2 of Halimath, Year %3 of the Third Age.}={#var dawn 5|#var night 21}