The insert below is from Wikipedia, basically they think that it means linking the cross with the sun:
"Popular legend in Ireland says that the Celtic Christian cross was introduced by Saint Patrick or possibly Saint Declan, though there are no examples from this early period. It has often been claimed that Patrick combined the symbol of Christianity with the sun cross to give pagan followers an idea of the importance of the cross. By linking it with the idea of the life-giving properties of the sun, these two ideas were linked to appeal to pagans. Other interpretations claim that placing the cross on top of the circle represents Christ's supremacy over the pagan sun."
The symbol for planet earth is a simple cross within a circle (like a 4 spoke wheel),not to be confused with the Celtic Cross (origin: Druid Sun Worship) or the Ku Klux Klan (origin: "Odin's Cross"
In Christianity the cross is a symbol for Jesus and the dove is a symbol for the Holy Spirit.
Do not dry clean
Don't dry clean
"bulb is circle and it have cross in it..."
It means somebody drew (or printed) a circle with a cross on it.To find out what it means on any specific map, you should consult the key and/or legend, which should tell you what each of the symbols mean.
I believe a circle within a circle is not part of Braille - Braille consists of a series of dots arranged in patterns.
A circle with a cross though it on clothes means do not dry clean. If there is a triangle with a cross it means do not use bleach.
The cross section of a circle is a circle. A circle is defined as a plane figure (i.e. 2 dimensional object) with a constant radius in both dimensions. Since a cross section is, by definition 2 dimensional, a circle's cross section is the circle itself.
You may mean the symbol for male, if so then the symbol for female is a circle patch with a cross.
A target
Concentric Circles?