diff --git a/android/assets/jsons/Buildings.json b/android/assets/jsons/Buildings.json
index fd184f0001..70aee274a9 100644
--- a/android/assets/jsons/Buildings.json
+++ b/android/assets/jsons/Buildings.json
@@ -226,7 +226,7 @@
 		hurryCostModifier:25,
 		percentStatBonus:{science:50},
 		requiredBuilding:"Library",
-		requiredTech:"Metal Casting"
+		requiredTech:"Astronomy"
 	}, 
 	{
 		name:"Opera House",
diff --git a/android/build.gradle b/android/build.gradle
index 4fe74d1cba..4006d7fdcd 100644
--- a/android/build.gradle
+++ b/android/build.gradle
@@ -21,7 +21,7 @@ android {
         applicationId "com.unciv.game"
         minSdkVersion 9
         targetSdkVersion 25
-        versionCode 9
+        versionCode 10
         versionName "0.9"
     }
     buildTypes {
diff --git a/core/src/com/unciv/civinfo/CityBuildings.java b/core/src/com/unciv/civinfo/CityBuildings.java
index d723ac7d67..e84ea10022 100644
--- a/core/src/com/unciv/civinfo/CityBuildings.java
+++ b/core/src/com/unciv/civinfo/CityBuildings.java
@@ -33,7 +33,7 @@ public class CityBuildings
 
     public CityInfo getCity(){return UnCivGame.Current.civInfo.tileMap.get(cityLocation).getCity(); }
     public boolean isBuilt(String buildingName) { return builtBuildings.contains(buildingName); }
-    public boolean isBuilding(String buildingName) { return currentBuilding.equals(buildingName); }
+    public boolean isBuilding(String buildingName) { return currentBuilding!=null && currentBuilding.equals(buildingName); }
 
     Building getGameBuilding(String buildingName) { return GameBasics.Buildings.get(buildingName); }
     public LinqCollection<Building> getBuiltBuildings(){ return  builtBuildings.select(new LinqCollection.Func<String, Building>() {
@@ -46,8 +46,8 @@ public class CityBuildings
     public void nextTurn(FullStats cityStats)
     {
         if (currentBuilding == null) return;
-        if(currentBuilding.equals("Gold")) {cityStats.gold+=cityStats.production/3; return;}
-        if(currentBuilding.equals("Science")) {cityStats.science+=cityStats.production/3; return;}
+        if(currentBuilding.equals("Gold")) {cityStats.gold+=cityStats.production/4; return;}
+        if(currentBuilding.equals("Science")) {cityStats.science+=cityStats.production/4; return;}
 
 
         Building gameBuilding = getGameBuilding(currentBuilding);
diff --git a/core/src/com/unciv/game/WorldScreen.java b/core/src/com/unciv/game/WorldScreen.java
index e2bc413b6c..120c1da1a8 100644
--- a/core/src/com/unciv/game/WorldScreen.java
+++ b/core/src/com/unciv/game/WorldScreen.java
@@ -462,9 +462,6 @@ public class WorldScreen extends com.unciv.game.utils.CameraStageBaseScreen {
     }
 
 
-
-
-
     void setCenterPosition(final Vector2 vector){
         TileGroup TG = tileGroups.linqValues().first(new Predicate<WorldTileGroup>() {
             @Override
@@ -480,10 +477,6 @@ public class WorldScreen extends com.unciv.game.utils.CameraStageBaseScreen {
         scrollPane.updateVisualScroll();
     }
 
-    float round(float value, int scale){
-        return (float) (Math.round(value * Math.pow(10, scale)) / Math.pow(10, scale));
-    }
-
 }
 
 
diff --git a/core/src/com/unciv/game/pickerscreens/BuildingPickerScreen.java b/core/src/com/unciv/game/pickerscreens/BuildingPickerScreen.java
index 201392f005..026ba09b69 100644
--- a/core/src/com/unciv/game/pickerscreens/BuildingPickerScreen.java
+++ b/core/src/com/unciv/game/pickerscreens/BuildingPickerScreen.java
@@ -72,11 +72,11 @@ public class BuildingPickerScreen extends PickerScreen {
 
         if(game.civInfo.tech.isResearched("Education"))
             specials.addActor(getProductionButton("Science","Produce Science",
-                    "Convert production to science at a rate of 3 to 1", "Produce Science"));
+                    "Convert production to science at a rate of 4 to 1", "Produce Science"));
 
         if(game.civInfo.tech.isResearched("Currency"))
             specials.addActor(getProductionButton("Gold","Produce Gold",
-                    "Convert production to gold at a rate of 3 to 1", "Produce Gold"));
+                    "Convert production to gold at a rate of 4 to 1", "Produce Gold"));
 
         topTable.add(regularBuildings);
         topTable.add(wonders);